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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Copyright (C) 2001 Momchil Velikov
4 * Portions Copyright (C) 2001 Christoph Hellwig
5 * Copyright (C) 2005 SGI, Christoph Lameter
6 * Copyright (C) 2006 Nick Piggin
7 * Copyright (C) 2012 Konstantin Khlebnikov
8 * Copyright (C) 2016 Intel, Matthew Wilcox
9 * Copyright (C) 2016 Intel, Ross Zwisler
10 */
11
12#include <linux/bitmap.h>
13#include <linux/bitops.h>
14#include <linux/bug.h>
15#include <linux/cpu.h>
16#include <linux/errno.h>
17#include <linux/export.h>
18#include <linux/idr.h>
19#include <linux/init.h>
20#include <linux/kernel.h>
21#include <linux/kmemleak.h>
22#include <linux/percpu.h>
23#include <linux/preempt.h> /* in_interrupt() */
24#include <linux/radix-tree.h>
25#include <linux/rcupdate.h>
26#include <linux/slab.h>
27#include <linux/string.h>
28#include <linux/xarray.h>
29
30/*
31 * Radix tree node cache.
32 */
33struct kmem_cache *radix_tree_node_cachep;
34
35/*
36 * The radix tree is variable-height, so an insert operation not only has
37 * to build the branch to its corresponding item, it also has to build the
38 * branch to existing items if the size has to be increased (by
39 * radix_tree_extend).
40 *
41 * The worst case is a zero height tree with just a single item at index 0,
42 * and then inserting an item at index ULONG_MAX. This requires 2 new branches
43 * of RADIX_TREE_MAX_PATH size to be created, with only the root node shared.
44 * Hence:
45 */
46#define RADIX_TREE_PRELOAD_SIZE (RADIX_TREE_MAX_PATH * 2 - 1)
47
48/*
49 * The IDR does not have to be as high as the radix tree since it uses
50 * signed integers, not unsigned longs.
51 */
52#define IDR_INDEX_BITS (8 /* CHAR_BIT */ * sizeof(int) - 1)
53#define IDR_MAX_PATH (DIV_ROUND_UP(IDR_INDEX_BITS, \
54 RADIX_TREE_MAP_SHIFT))
55#define IDR_PRELOAD_SIZE (IDR_MAX_PATH * 2 - 1)
56
57/*
58 * Per-cpu pool of preloaded nodes
59 */
60DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = {
61 .lock = INIT_LOCAL_LOCK(lock),
62};
63EXPORT_PER_CPU_SYMBOL_GPL(radix_tree_preloads);
64
65static inline struct radix_tree_node *entry_to_node(void *ptr)
66{
67 return (void *)((unsigned long)ptr & ~RADIX_TREE_INTERNAL_NODE);
68}
69
70static inline void *node_to_entry(void *ptr)
71{
72 return (void *)((unsigned long)ptr | RADIX_TREE_INTERNAL_NODE);
73}
74
75#define RADIX_TREE_RETRY XA_RETRY_ENTRY
76
77static inline unsigned long
78get_slot_offset(const struct radix_tree_node *parent, void __rcu **slot)
79{
80 return parent ? slot - parent->slots : 0;
81}
82
83static unsigned int radix_tree_descend(const struct radix_tree_node *parent,
84 struct radix_tree_node **nodep, unsigned long index)
85{
86 unsigned int offset = (index >> parent->shift) & RADIX_TREE_MAP_MASK;
87 void __rcu **entry = rcu_dereference_raw(parent->slots[offset]);
88
89 *nodep = (void *)entry;
90 return offset;
91}
92
93static inline gfp_t root_gfp_mask(const struct radix_tree_root *root)
94{
95 return root->xa_flags & (__GFP_BITS_MASK & ~GFP_ZONEMASK);
96}
97
98static inline void tag_set(struct radix_tree_node *node, unsigned int tag,
99 int offset)
100{
101 __set_bit(offset, node->tags[tag]);
102}
103
104static inline void tag_clear(struct radix_tree_node *node, unsigned int tag,
105 int offset)
106{
107 __clear_bit(offset, node->tags[tag]);
108}
109
110static inline int tag_get(const struct radix_tree_node *node, unsigned int tag,
111 int offset)
112{
113 return test_bit(offset, node->tags[tag]);
114}
115
116static inline void root_tag_set(struct radix_tree_root *root, unsigned tag)
117{
118 root->xa_flags |= (__force gfp_t)(1 << (tag + ROOT_TAG_SHIFT));
119}
120
121static inline void root_tag_clear(struct radix_tree_root *root, unsigned tag)
122{
123 root->xa_flags &= (__force gfp_t)~(1 << (tag + ROOT_TAG_SHIFT));
124}
125
126static inline void root_tag_clear_all(struct radix_tree_root *root)
127{
128 root->xa_flags &= (__force gfp_t)((1 << ROOT_TAG_SHIFT) - 1);
129}
130
131static inline int root_tag_get(const struct radix_tree_root *root, unsigned tag)
132{
133 return (__force int)root->xa_flags & (1 << (tag + ROOT_TAG_SHIFT));
134}
135
136static inline unsigned root_tags_get(const struct radix_tree_root *root)
137{
138 return (__force unsigned)root->xa_flags >> ROOT_TAG_SHIFT;
139}
140
141static inline bool is_idr(const struct radix_tree_root *root)
142{
143 return !!(root->xa_flags & ROOT_IS_IDR);
144}
145
146/*
147 * Returns 1 if any slot in the node has this tag set.
148 * Otherwise returns 0.
149 */
150static inline int any_tag_set(const struct radix_tree_node *node,
151 unsigned int tag)
152{
153 unsigned idx;
154 for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) {
155 if (node->tags[tag][idx])
156 return 1;
157 }
158 return 0;
159}
160
161static inline void all_tag_set(struct radix_tree_node *node, unsigned int tag)
162{
163 bitmap_fill(node->tags[tag], RADIX_TREE_MAP_SIZE);
164}
165
166/**
167 * radix_tree_find_next_bit - find the next set bit in a memory region
168 *
169 * @node: where to begin the search
170 * @tag: the tag index
171 * @offset: the bitnumber to start searching at
172 *
173 * Unrollable variant of find_next_bit() for constant size arrays.
174 * Tail bits starting from size to roundup(size, BITS_PER_LONG) must be zero.
175 * Returns next bit offset, or size if nothing found.
176 */
177static __always_inline unsigned long
178radix_tree_find_next_bit(struct radix_tree_node *node, unsigned int tag,
179 unsigned long offset)
180{
181 const unsigned long *addr = node->tags[tag];
182
183 if (offset < RADIX_TREE_MAP_SIZE) {
184 unsigned long tmp;
185
186 addr += offset / BITS_PER_LONG;
187 tmp = *addr >> (offset % BITS_PER_LONG);
188 if (tmp)
189 return __ffs(tmp) + offset;
190 offset = (offset + BITS_PER_LONG) & ~(BITS_PER_LONG - 1);
191 while (offset < RADIX_TREE_MAP_SIZE) {
192 tmp = *++addr;
193 if (tmp)
194 return __ffs(tmp) + offset;
195 offset += BITS_PER_LONG;
196 }
197 }
198 return RADIX_TREE_MAP_SIZE;
199}
200
201static unsigned int iter_offset(const struct radix_tree_iter *iter)
202{
203 return iter->index & RADIX_TREE_MAP_MASK;
204}
205
206/*
207 * The maximum index which can be stored in a radix tree
208 */
209static inline unsigned long shift_maxindex(unsigned int shift)
210{
211 return (RADIX_TREE_MAP_SIZE << shift) - 1;
212}
213
214static inline unsigned long node_maxindex(const struct radix_tree_node *node)
215{
216 return shift_maxindex(node->shift);
217}
218
219static unsigned long next_index(unsigned long index,
220 const struct radix_tree_node *node,
221 unsigned long offset)
222{
223 return (index & ~node_maxindex(node)) + (offset << node->shift);
224}
225
226/*
227 * This assumes that the caller has performed appropriate preallocation, and
228 * that the caller has pinned this thread of control to the current CPU.
229 */
230static struct radix_tree_node *
231radix_tree_node_alloc(gfp_t gfp_mask, struct radix_tree_node *parent,
232 struct radix_tree_root *root,
233 unsigned int shift, unsigned int offset,
234 unsigned int count, unsigned int nr_values)
235{
236 struct radix_tree_node *ret = NULL;
237
238 /*
239 * Preload code isn't irq safe and it doesn't make sense to use
240 * preloading during an interrupt anyway as all the allocations have
241 * to be atomic. So just do normal allocation when in interrupt.
242 */
243 if (!gfpflags_allow_blocking(gfp_mask) && !in_interrupt()) {
244 struct radix_tree_preload *rtp;
245
246 /*
247 * Even if the caller has preloaded, try to allocate from the
248 * cache first for the new node to get accounted to the memory
249 * cgroup.
250 */
251 ret = kmem_cache_alloc(radix_tree_node_cachep,
252 gfp_mask | __GFP_NOWARN);
253 if (ret)
254 goto out;
255
256 /*
257 * Provided the caller has preloaded here, we will always
258 * succeed in getting a node here (and never reach
259 * kmem_cache_alloc)
260 */
261 rtp = this_cpu_ptr(&radix_tree_preloads);
262 if (rtp->nr) {
263 ret = rtp->nodes;
264 rtp->nodes = ret->parent;
265 rtp->nr--;
266 }
267 /*
268 * Update the allocation stack trace as this is more useful
269 * for debugging.
270 */
271 kmemleak_update_trace(ret);
272 goto out;
273 }
274 ret = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask);
275out:
276 BUG_ON(radix_tree_is_internal_node(ret));
277 if (ret) {
278 ret->shift = shift;
279 ret->offset = offset;
280 ret->count = count;
281 ret->nr_values = nr_values;
282 ret->parent = parent;
283 ret->array = root;
284 }
285 return ret;
286}
287
288void radix_tree_node_rcu_free(struct rcu_head *head)
289{
290 struct radix_tree_node *node =
291 container_of(head, struct radix_tree_node, rcu_head);
292
293 /*
294 * Must only free zeroed nodes into the slab. We can be left with
295 * non-NULL entries by radix_tree_free_nodes, so clear the entries
296 * and tags here.
297 */
298 memset(node->slots, 0, sizeof(node->slots));
299 memset(node->tags, 0, sizeof(node->tags));
300 INIT_LIST_HEAD(&node->private_list);
301
302 kmem_cache_free(radix_tree_node_cachep, node);
303}
304
305static inline void
306radix_tree_node_free(struct radix_tree_node *node)
307{
308 call_rcu(&node->rcu_head, radix_tree_node_rcu_free);
309}
310
311/*
312 * Load up this CPU's radix_tree_node buffer with sufficient objects to
313 * ensure that the addition of a single element in the tree cannot fail. On
314 * success, return zero, with preemption disabled. On error, return -ENOMEM
315 * with preemption not disabled.
316 *
317 * To make use of this facility, the radix tree must be initialised without
318 * __GFP_DIRECT_RECLAIM being passed to INIT_RADIX_TREE().
319 */
320static __must_check int __radix_tree_preload(gfp_t gfp_mask, unsigned nr)
321{
322 struct radix_tree_preload *rtp;
323 struct radix_tree_node *node;
324 int ret = -ENOMEM;
325
326 /*
327 * Nodes preloaded by one cgroup can be used by another cgroup, so
328 * they should never be accounted to any particular memory cgroup.
329 */
330 gfp_mask &= ~__GFP_ACCOUNT;
331
332 local_lock(&radix_tree_preloads.lock);
333 rtp = this_cpu_ptr(&radix_tree_preloads);
334 while (rtp->nr < nr) {
335 local_unlock(&radix_tree_preloads.lock);
336 node = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask);
337 if (node == NULL)
338 goto out;
339 local_lock(&radix_tree_preloads.lock);
340 rtp = this_cpu_ptr(&radix_tree_preloads);
341 if (rtp->nr < nr) {
342 node->parent = rtp->nodes;
343 rtp->nodes = node;
344 rtp->nr++;
345 } else {
346 kmem_cache_free(radix_tree_node_cachep, node);
347 }
348 }
349 ret = 0;
350out:
351 return ret;
352}
353
354/*
355 * Load up this CPU's radix_tree_node buffer with sufficient objects to
356 * ensure that the addition of a single element in the tree cannot fail. On
357 * success, return zero, with preemption disabled. On error, return -ENOMEM
358 * with preemption not disabled.
359 *
360 * To make use of this facility, the radix tree must be initialised without
361 * __GFP_DIRECT_RECLAIM being passed to INIT_RADIX_TREE().
362 */
363int radix_tree_preload(gfp_t gfp_mask)
364{
365 /* Warn on non-sensical use... */
366 WARN_ON_ONCE(!gfpflags_allow_blocking(gfp_mask));
367 return __radix_tree_preload(gfp_mask, RADIX_TREE_PRELOAD_SIZE);
368}
369EXPORT_SYMBOL(radix_tree_preload);
370
371/*
372 * The same as above function, except we don't guarantee preloading happens.
373 * We do it, if we decide it helps. On success, return zero with preemption
374 * disabled. On error, return -ENOMEM with preemption not disabled.
375 */
376int radix_tree_maybe_preload(gfp_t gfp_mask)
377{
378 if (gfpflags_allow_blocking(gfp_mask))
379 return __radix_tree_preload(gfp_mask, RADIX_TREE_PRELOAD_SIZE);
380 /* Preloading doesn't help anything with this gfp mask, skip it */
381 local_lock(&radix_tree_preloads.lock);
382 return 0;
383}
384EXPORT_SYMBOL(radix_tree_maybe_preload);
385
386static unsigned radix_tree_load_root(const struct radix_tree_root *root,
387 struct radix_tree_node **nodep, unsigned long *maxindex)
388{
389 struct radix_tree_node *node = rcu_dereference_raw(root->xa_head);
390
391 *nodep = node;
392
393 if (likely(radix_tree_is_internal_node(node))) {
394 node = entry_to_node(node);
395 *maxindex = node_maxindex(node);
396 return node->shift + RADIX_TREE_MAP_SHIFT;
397 }
398
399 *maxindex = 0;
400 return 0;
401}
402
403/*
404 * Extend a radix tree so it can store key @index.
405 */
406static int radix_tree_extend(struct radix_tree_root *root, gfp_t gfp,
407 unsigned long index, unsigned int shift)
408{
409 void *entry;
410 unsigned int maxshift;
411 int tag;
412
413 /* Figure out what the shift should be. */
414 maxshift = shift;
415 while (index > shift_maxindex(maxshift))
416 maxshift += RADIX_TREE_MAP_SHIFT;
417
418 entry = rcu_dereference_raw(root->xa_head);
419 if (!entry && (!is_idr(root) || root_tag_get(root, IDR_FREE)))
420 goto out;
421
422 do {
423 struct radix_tree_node *node = radix_tree_node_alloc(gfp, NULL,
424 root, shift, 0, 1, 0);
425 if (!node)
426 return -ENOMEM;
427
428 if (is_idr(root)) {
429 all_tag_set(node, IDR_FREE);
430 if (!root_tag_get(root, IDR_FREE)) {
431 tag_clear(node, IDR_FREE, 0);
432 root_tag_set(root, IDR_FREE);
433 }
434 } else {
435 /* Propagate the aggregated tag info to the new child */
436 for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
437 if (root_tag_get(root, tag))
438 tag_set(node, tag, 0);
439 }
440 }
441
442 BUG_ON(shift > BITS_PER_LONG);
443 if (radix_tree_is_internal_node(entry)) {
444 entry_to_node(entry)->parent = node;
445 } else if (xa_is_value(entry)) {
446 /* Moving a value entry root->xa_head to a node */
447 node->nr_values = 1;
448 }
449 /*
450 * entry was already in the radix tree, so we do not need
451 * rcu_assign_pointer here
452 */
453 node->slots[0] = (void __rcu *)entry;
454 entry = node_to_entry(node);
455 rcu_assign_pointer(root->xa_head, entry);
456 shift += RADIX_TREE_MAP_SHIFT;
457 } while (shift <= maxshift);
458out:
459 return maxshift + RADIX_TREE_MAP_SHIFT;
460}
461
462/**
463 * radix_tree_shrink - shrink radix tree to minimum height
464 * @root: radix tree root
465 */
466static inline bool radix_tree_shrink(struct radix_tree_root *root)
467{
468 bool shrunk = false;
469
470 for (;;) {
471 struct radix_tree_node *node = rcu_dereference_raw(root->xa_head);
472 struct radix_tree_node *child;
473
474 if (!radix_tree_is_internal_node(node))
475 break;
476 node = entry_to_node(node);
477
478 /*
479 * The candidate node has more than one child, or its child
480 * is not at the leftmost slot, we cannot shrink.
481 */
482 if (node->count != 1)
483 break;
484 child = rcu_dereference_raw(node->slots[0]);
485 if (!child)
486 break;
487
488 /*
489 * For an IDR, we must not shrink entry 0 into the root in
490 * case somebody calls idr_replace() with a pointer that
491 * appears to be an internal entry
492 */
493 if (!node->shift && is_idr(root))
494 break;
495
496 if (radix_tree_is_internal_node(child))
497 entry_to_node(child)->parent = NULL;
498
499 /*
500 * We don't need rcu_assign_pointer(), since we are simply
501 * moving the node from one part of the tree to another: if it
502 * was safe to dereference the old pointer to it
503 * (node->slots[0]), it will be safe to dereference the new
504 * one (root->xa_head) as far as dependent read barriers go.
505 */
506 root->xa_head = (void __rcu *)child;
507 if (is_idr(root) && !tag_get(node, IDR_FREE, 0))
508 root_tag_clear(root, IDR_FREE);
509
510 /*
511 * We have a dilemma here. The node's slot[0] must not be
512 * NULLed in case there are concurrent lookups expecting to
513 * find the item. However if this was a bottom-level node,
514 * then it may be subject to the slot pointer being visible
515 * to callers dereferencing it. If item corresponding to
516 * slot[0] is subsequently deleted, these callers would expect
517 * their slot to become empty sooner or later.
518 *
519 * For example, lockless pagecache will look up a slot, deref
520 * the page pointer, and if the page has 0 refcount it means it
521 * was concurrently deleted from pagecache so try the deref
522 * again. Fortunately there is already a requirement for logic
523 * to retry the entire slot lookup -- the indirect pointer
524 * problem (replacing direct root node with an indirect pointer
525 * also results in a stale slot). So tag the slot as indirect
526 * to force callers to retry.
527 */
528 node->count = 0;
529 if (!radix_tree_is_internal_node(child)) {
530 node->slots[0] = (void __rcu *)RADIX_TREE_RETRY;
531 }
532
533 WARN_ON_ONCE(!list_empty(&node->private_list));
534 radix_tree_node_free(node);
535 shrunk = true;
536 }
537
538 return shrunk;
539}
540
541static bool delete_node(struct radix_tree_root *root,
542 struct radix_tree_node *node)
543{
544 bool deleted = false;
545
546 do {
547 struct radix_tree_node *parent;
548
549 if (node->count) {
550 if (node_to_entry(node) ==
551 rcu_dereference_raw(root->xa_head))
552 deleted |= radix_tree_shrink(root);
553 return deleted;
554 }
555
556 parent = node->parent;
557 if (parent) {
558 parent->slots[node->offset] = NULL;
559 parent->count--;
560 } else {
561 /*
562 * Shouldn't the tags already have all been cleared
563 * by the caller?
564 */
565 if (!is_idr(root))
566 root_tag_clear_all(root);
567 root->xa_head = NULL;
568 }
569
570 WARN_ON_ONCE(!list_empty(&node->private_list));
571 radix_tree_node_free(node);
572 deleted = true;
573
574 node = parent;
575 } while (node);
576
577 return deleted;
578}
579
580/**
581 * __radix_tree_create - create a slot in a radix tree
582 * @root: radix tree root
583 * @index: index key
584 * @nodep: returns node
585 * @slotp: returns slot
586 *
587 * Create, if necessary, and return the node and slot for an item
588 * at position @index in the radix tree @root.
589 *
590 * Until there is more than one item in the tree, no nodes are
591 * allocated and @root->xa_head is used as a direct slot instead of
592 * pointing to a node, in which case *@nodep will be NULL.
593 *
594 * Returns -ENOMEM, or 0 for success.
595 */
596static int __radix_tree_create(struct radix_tree_root *root,
597 unsigned long index, struct radix_tree_node **nodep,
598 void __rcu ***slotp)
599{
600 struct radix_tree_node *node = NULL, *child;
601 void __rcu **slot = (void __rcu **)&root->xa_head;
602 unsigned long maxindex;
603 unsigned int shift, offset = 0;
604 unsigned long max = index;
605 gfp_t gfp = root_gfp_mask(root);
606
607 shift = radix_tree_load_root(root, &child, &maxindex);
608
609 /* Make sure the tree is high enough. */
610 if (max > maxindex) {
611 int error = radix_tree_extend(root, gfp, max, shift);
612 if (error < 0)
613 return error;
614 shift = error;
615 child = rcu_dereference_raw(root->xa_head);
616 }
617
618 while (shift > 0) {
619 shift -= RADIX_TREE_MAP_SHIFT;
620 if (child == NULL) {
621 /* Have to add a child node. */
622 child = radix_tree_node_alloc(gfp, node, root, shift,
623 offset, 0, 0);
624 if (!child)
625 return -ENOMEM;
626 rcu_assign_pointer(*slot, node_to_entry(child));
627 if (node)
628 node->count++;
629 } else if (!radix_tree_is_internal_node(child))
630 break;
631
632 /* Go a level down */
633 node = entry_to_node(child);
634 offset = radix_tree_descend(node, &child, index);
635 slot = &node->slots[offset];
636 }
637
638 if (nodep)
639 *nodep = node;
640 if (slotp)
641 *slotp = slot;
642 return 0;
643}
644
645/*
646 * Free any nodes below this node. The tree is presumed to not need
647 * shrinking, and any user data in the tree is presumed to not need a
648 * destructor called on it. If we need to add a destructor, we can
649 * add that functionality later. Note that we may not clear tags or
650 * slots from the tree as an RCU walker may still have a pointer into
651 * this subtree. We could replace the entries with RADIX_TREE_RETRY,
652 * but we'll still have to clear those in rcu_free.
653 */
654static void radix_tree_free_nodes(struct radix_tree_node *node)
655{
656 unsigned offset = 0;
657 struct radix_tree_node *child = entry_to_node(node);
658
659 for (;;) {
660 void *entry = rcu_dereference_raw(child->slots[offset]);
661 if (xa_is_node(entry) && child->shift) {
662 child = entry_to_node(entry);
663 offset = 0;
664 continue;
665 }
666 offset++;
667 while (offset == RADIX_TREE_MAP_SIZE) {
668 struct radix_tree_node *old = child;
669 offset = child->offset + 1;
670 child = child->parent;
671 WARN_ON_ONCE(!list_empty(&old->private_list));
672 radix_tree_node_free(old);
673 if (old == entry_to_node(node))
674 return;
675 }
676 }
677}
678
679static inline int insert_entries(struct radix_tree_node *node,
680 void __rcu **slot, void *item, bool replace)
681{
682 if (*slot)
683 return -EEXIST;
684 rcu_assign_pointer(*slot, item);
685 if (node) {
686 node->count++;
687 if (xa_is_value(item))
688 node->nr_values++;
689 }
690 return 1;
691}
692
693/**
694 * radix_tree_insert - insert into a radix tree
695 * @root: radix tree root
696 * @index: index key
697 * @item: item to insert
698 *
699 * Insert an item into the radix tree at position @index.
700 */
701int radix_tree_insert(struct radix_tree_root *root, unsigned long index,
702 void *item)
703{
704 struct radix_tree_node *node;
705 void __rcu **slot;
706 int error;
707
708 BUG_ON(radix_tree_is_internal_node(item));
709
710 error = __radix_tree_create(root, index, &node, &slot);
711 if (error)
712 return error;
713
714 error = insert_entries(node, slot, item, false);
715 if (error < 0)
716 return error;
717
718 if (node) {
719 unsigned offset = get_slot_offset(node, slot);
720 BUG_ON(tag_get(node, 0, offset));
721 BUG_ON(tag_get(node, 1, offset));
722 BUG_ON(tag_get(node, 2, offset));
723 } else {
724 BUG_ON(root_tags_get(root));
725 }
726
727 return 0;
728}
729EXPORT_SYMBOL(radix_tree_insert);
730
731/**
732 * __radix_tree_lookup - lookup an item in a radix tree
733 * @root: radix tree root
734 * @index: index key
735 * @nodep: returns node
736 * @slotp: returns slot
737 *
738 * Lookup and return the item at position @index in the radix
739 * tree @root.
740 *
741 * Until there is more than one item in the tree, no nodes are
742 * allocated and @root->xa_head is used as a direct slot instead of
743 * pointing to a node, in which case *@nodep will be NULL.
744 */
745void *__radix_tree_lookup(const struct radix_tree_root *root,
746 unsigned long index, struct radix_tree_node **nodep,
747 void __rcu ***slotp)
748{
749 struct radix_tree_node *node, *parent;
750 unsigned long maxindex;
751 void __rcu **slot;
752
753 restart:
754 parent = NULL;
755 slot = (void __rcu **)&root->xa_head;
756 radix_tree_load_root(root, &node, &maxindex);
757 if (index > maxindex)
758 return NULL;
759
760 while (radix_tree_is_internal_node(node)) {
761 unsigned offset;
762
763 parent = entry_to_node(node);
764 offset = radix_tree_descend(parent, &node, index);
765 slot = parent->slots + offset;
766 if (node == RADIX_TREE_RETRY)
767 goto restart;
768 if (parent->shift == 0)
769 break;
770 }
771
772 if (nodep)
773 *nodep = parent;
774 if (slotp)
775 *slotp = slot;
776 return node;
777}
778
779/**
780 * radix_tree_lookup_slot - lookup a slot in a radix tree
781 * @root: radix tree root
782 * @index: index key
783 *
784 * Returns: the slot corresponding to the position @index in the
785 * radix tree @root. This is useful for update-if-exists operations.
786 *
787 * This function can be called under rcu_read_lock iff the slot is not
788 * modified by radix_tree_replace_slot, otherwise it must be called
789 * exclusive from other writers. Any dereference of the slot must be done
790 * using radix_tree_deref_slot.
791 */
792void __rcu **radix_tree_lookup_slot(const struct radix_tree_root *root,
793 unsigned long index)
794{
795 void __rcu **slot;
796
797 if (!__radix_tree_lookup(root, index, NULL, &slot))
798 return NULL;
799 return slot;
800}
801EXPORT_SYMBOL(radix_tree_lookup_slot);
802
803/**
804 * radix_tree_lookup - perform lookup operation on a radix tree
805 * @root: radix tree root
806 * @index: index key
807 *
808 * Lookup the item at the position @index in the radix tree @root.
809 *
810 * This function can be called under rcu_read_lock, however the caller
811 * must manage lifetimes of leaf nodes (eg. RCU may also be used to free
812 * them safely). No RCU barriers are required to access or modify the
813 * returned item, however.
814 */
815void *radix_tree_lookup(const struct radix_tree_root *root, unsigned long index)
816{
817 return __radix_tree_lookup(root, index, NULL, NULL);
818}
819EXPORT_SYMBOL(radix_tree_lookup);
820
821static void replace_slot(void __rcu **slot, void *item,
822 struct radix_tree_node *node, int count, int values)
823{
824 if (node && (count || values)) {
825 node->count += count;
826 node->nr_values += values;
827 }
828
829 rcu_assign_pointer(*slot, item);
830}
831
832static bool node_tag_get(const struct radix_tree_root *root,
833 const struct radix_tree_node *node,
834 unsigned int tag, unsigned int offset)
835{
836 if (node)
837 return tag_get(node, tag, offset);
838 return root_tag_get(root, tag);
839}
840
841/*
842 * IDR users want to be able to store NULL in the tree, so if the slot isn't
843 * free, don't adjust the count, even if it's transitioning between NULL and
844 * non-NULL. For the IDA, we mark slots as being IDR_FREE while they still
845 * have empty bits, but it only stores NULL in slots when they're being
846 * deleted.
847 */
848static int calculate_count(struct radix_tree_root *root,
849 struct radix_tree_node *node, void __rcu **slot,
850 void *item, void *old)
851{
852 if (is_idr(root)) {
853 unsigned offset = get_slot_offset(node, slot);
854 bool free = node_tag_get(root, node, IDR_FREE, offset);
855 if (!free)
856 return 0;
857 if (!old)
858 return 1;
859 }
860 return !!item - !!old;
861}
862
863/**
864 * __radix_tree_replace - replace item in a slot
865 * @root: radix tree root
866 * @node: pointer to tree node
867 * @slot: pointer to slot in @node
868 * @item: new item to store in the slot.
869 *
870 * For use with __radix_tree_lookup(). Caller must hold tree write locked
871 * across slot lookup and replacement.
872 */
873void __radix_tree_replace(struct radix_tree_root *root,
874 struct radix_tree_node *node,
875 void __rcu **slot, void *item)
876{
877 void *old = rcu_dereference_raw(*slot);
878 int values = !!xa_is_value(item) - !!xa_is_value(old);
879 int count = calculate_count(root, node, slot, item, old);
880
881 /*
882 * This function supports replacing value entries and
883 * deleting entries, but that needs accounting against the
884 * node unless the slot is root->xa_head.
885 */
886 WARN_ON_ONCE(!node && (slot != (void __rcu **)&root->xa_head) &&
887 (count || values));
888 replace_slot(slot, item, node, count, values);
889
890 if (!node)
891 return;
892
893 delete_node(root, node);
894}
895
896/**
897 * radix_tree_replace_slot - replace item in a slot
898 * @root: radix tree root
899 * @slot: pointer to slot
900 * @item: new item to store in the slot.
901 *
902 * For use with radix_tree_lookup_slot() and
903 * radix_tree_gang_lookup_tag_slot(). Caller must hold tree write locked
904 * across slot lookup and replacement.
905 *
906 * NOTE: This cannot be used to switch between non-entries (empty slots),
907 * regular entries, and value entries, as that requires accounting
908 * inside the radix tree node. When switching from one type of entry or
909 * deleting, use __radix_tree_lookup() and __radix_tree_replace() or
910 * radix_tree_iter_replace().
911 */
912void radix_tree_replace_slot(struct radix_tree_root *root,
913 void __rcu **slot, void *item)
914{
915 __radix_tree_replace(root, NULL, slot, item);
916}
917EXPORT_SYMBOL(radix_tree_replace_slot);
918
919/**
920 * radix_tree_iter_replace - replace item in a slot
921 * @root: radix tree root
922 * @iter: iterator state
923 * @slot: pointer to slot
924 * @item: new item to store in the slot.
925 *
926 * For use with radix_tree_for_each_slot().
927 * Caller must hold tree write locked.
928 */
929void radix_tree_iter_replace(struct radix_tree_root *root,
930 const struct radix_tree_iter *iter,
931 void __rcu **slot, void *item)
932{
933 __radix_tree_replace(root, iter->node, slot, item);
934}
935
936static void node_tag_set(struct radix_tree_root *root,
937 struct radix_tree_node *node,
938 unsigned int tag, unsigned int offset)
939{
940 while (node) {
941 if (tag_get(node, tag, offset))
942 return;
943 tag_set(node, tag, offset);
944 offset = node->offset;
945 node = node->parent;
946 }
947
948 if (!root_tag_get(root, tag))
949 root_tag_set(root, tag);
950}
951
952/**
953 * radix_tree_tag_set - set a tag on a radix tree node
954 * @root: radix tree root
955 * @index: index key
956 * @tag: tag index
957 *
958 * Set the search tag (which must be < RADIX_TREE_MAX_TAGS)
959 * corresponding to @index in the radix tree. From
960 * the root all the way down to the leaf node.
961 *
962 * Returns the address of the tagged item. Setting a tag on a not-present
963 * item is a bug.
964 */
965void *radix_tree_tag_set(struct radix_tree_root *root,
966 unsigned long index, unsigned int tag)
967{
968 struct radix_tree_node *node, *parent;
969 unsigned long maxindex;
970
971 radix_tree_load_root(root, &node, &maxindex);
972 BUG_ON(index > maxindex);
973
974 while (radix_tree_is_internal_node(node)) {
975 unsigned offset;
976
977 parent = entry_to_node(node);
978 offset = radix_tree_descend(parent, &node, index);
979 BUG_ON(!node);
980
981 if (!tag_get(parent, tag, offset))
982 tag_set(parent, tag, offset);
983 }
984
985 /* set the root's tag bit */
986 if (!root_tag_get(root, tag))
987 root_tag_set(root, tag);
988
989 return node;
990}
991EXPORT_SYMBOL(radix_tree_tag_set);
992
993static void node_tag_clear(struct radix_tree_root *root,
994 struct radix_tree_node *node,
995 unsigned int tag, unsigned int offset)
996{
997 while (node) {
998 if (!tag_get(node, tag, offset))
999 return;
1000 tag_clear(node, tag, offset);
1001 if (any_tag_set(node, tag))
1002 return;
1003
1004 offset = node->offset;
1005 node = node->parent;
1006 }
1007
1008 /* clear the root's tag bit */
1009 if (root_tag_get(root, tag))
1010 root_tag_clear(root, tag);
1011}
1012
1013/**
1014 * radix_tree_tag_clear - clear a tag on a radix tree node
1015 * @root: radix tree root
1016 * @index: index key
1017 * @tag: tag index
1018 *
1019 * Clear the search tag (which must be < RADIX_TREE_MAX_TAGS)
1020 * corresponding to @index in the radix tree. If this causes
1021 * the leaf node to have no tags set then clear the tag in the
1022 * next-to-leaf node, etc.
1023 *
1024 * Returns the address of the tagged item on success, else NULL. ie:
1025 * has the same return value and semantics as radix_tree_lookup().
1026 */
1027void *radix_tree_tag_clear(struct radix_tree_root *root,
1028 unsigned long index, unsigned int tag)
1029{
1030 struct radix_tree_node *node, *parent;
1031 unsigned long maxindex;
1032 int offset;
1033
1034 radix_tree_load_root(root, &node, &maxindex);
1035 if (index > maxindex)
1036 return NULL;
1037
1038 parent = NULL;
1039
1040 while (radix_tree_is_internal_node(node)) {
1041 parent = entry_to_node(node);
1042 offset = radix_tree_descend(parent, &node, index);
1043 }
1044
1045 if (node)
1046 node_tag_clear(root, parent, tag, offset);
1047
1048 return node;
1049}
1050EXPORT_SYMBOL(radix_tree_tag_clear);
1051
1052/**
1053 * radix_tree_iter_tag_clear - clear a tag on the current iterator entry
1054 * @root: radix tree root
1055 * @iter: iterator state
1056 * @tag: tag to clear
1057 */
1058void radix_tree_iter_tag_clear(struct radix_tree_root *root,
1059 const struct radix_tree_iter *iter, unsigned int tag)
1060{
1061 node_tag_clear(root, iter->node, tag, iter_offset(iter));
1062}
1063
1064/**
1065 * radix_tree_tag_get - get a tag on a radix tree node
1066 * @root: radix tree root
1067 * @index: index key
1068 * @tag: tag index (< RADIX_TREE_MAX_TAGS)
1069 *
1070 * Return values:
1071 *
1072 * 0: tag not present or not set
1073 * 1: tag set
1074 *
1075 * Note that the return value of this function may not be relied on, even if
1076 * the RCU lock is held, unless tag modification and node deletion are excluded
1077 * from concurrency.
1078 */
1079int radix_tree_tag_get(const struct radix_tree_root *root,
1080 unsigned long index, unsigned int tag)
1081{
1082 struct radix_tree_node *node, *parent;
1083 unsigned long maxindex;
1084
1085 if (!root_tag_get(root, tag))
1086 return 0;
1087
1088 radix_tree_load_root(root, &node, &maxindex);
1089 if (index > maxindex)
1090 return 0;
1091
1092 while (radix_tree_is_internal_node(node)) {
1093 unsigned offset;
1094
1095 parent = entry_to_node(node);
1096 offset = radix_tree_descend(parent, &node, index);
1097
1098 if (!tag_get(parent, tag, offset))
1099 return 0;
1100 if (node == RADIX_TREE_RETRY)
1101 break;
1102 }
1103
1104 return 1;
1105}
1106EXPORT_SYMBOL(radix_tree_tag_get);
1107
1108/* Construct iter->tags bit-mask from node->tags[tag] array */
1109static void set_iter_tags(struct radix_tree_iter *iter,
1110 struct radix_tree_node *node, unsigned offset,
1111 unsigned tag)
1112{
1113 unsigned tag_long = offset / BITS_PER_LONG;
1114 unsigned tag_bit = offset % BITS_PER_LONG;
1115
1116 if (!node) {
1117 iter->tags = 1;
1118 return;
1119 }
1120
1121 iter->tags = node->tags[tag][tag_long] >> tag_bit;
1122
1123 /* This never happens if RADIX_TREE_TAG_LONGS == 1 */
1124 if (tag_long < RADIX_TREE_TAG_LONGS - 1) {
1125 /* Pick tags from next element */
1126 if (tag_bit)
1127 iter->tags |= node->tags[tag][tag_long + 1] <<
1128 (BITS_PER_LONG - tag_bit);
1129 /* Clip chunk size, here only BITS_PER_LONG tags */
1130 iter->next_index = __radix_tree_iter_add(iter, BITS_PER_LONG);
1131 }
1132}
1133
1134void __rcu **radix_tree_iter_resume(void __rcu **slot,
1135 struct radix_tree_iter *iter)
1136{
1137 slot++;
1138 iter->index = __radix_tree_iter_add(iter, 1);
1139 iter->next_index = iter->index;
1140 iter->tags = 0;
1141 return NULL;
1142}
1143EXPORT_SYMBOL(radix_tree_iter_resume);
1144
1145/**
1146 * radix_tree_next_chunk - find next chunk of slots for iteration
1147 *
1148 * @root: radix tree root
1149 * @iter: iterator state
1150 * @flags: RADIX_TREE_ITER_* flags and tag index
1151 * Returns: pointer to chunk first slot, or NULL if iteration is over
1152 */
1153void __rcu **radix_tree_next_chunk(const struct radix_tree_root *root,
1154 struct radix_tree_iter *iter, unsigned flags)
1155{
1156 unsigned tag = flags & RADIX_TREE_ITER_TAG_MASK;
1157 struct radix_tree_node *node, *child;
1158 unsigned long index, offset, maxindex;
1159
1160 if ((flags & RADIX_TREE_ITER_TAGGED) && !root_tag_get(root, tag))
1161 return NULL;
1162
1163 /*
1164 * Catch next_index overflow after ~0UL. iter->index never overflows
1165 * during iterating; it can be zero only at the beginning.
1166 * And we cannot overflow iter->next_index in a single step,
1167 * because RADIX_TREE_MAP_SHIFT < BITS_PER_LONG.
1168 *
1169 * This condition also used by radix_tree_next_slot() to stop
1170 * contiguous iterating, and forbid switching to the next chunk.
1171 */
1172 index = iter->next_index;
1173 if (!index && iter->index)
1174 return NULL;
1175
1176 restart:
1177 radix_tree_load_root(root, &child, &maxindex);
1178 if (index > maxindex)
1179 return NULL;
1180 if (!child)
1181 return NULL;
1182
1183 if (!radix_tree_is_internal_node(child)) {
1184 /* Single-slot tree */
1185 iter->index = index;
1186 iter->next_index = maxindex + 1;
1187 iter->tags = 1;
1188 iter->node = NULL;
1189 return (void __rcu **)&root->xa_head;
1190 }
1191
1192 do {
1193 node = entry_to_node(child);
1194 offset = radix_tree_descend(node, &child, index);
1195
1196 if ((flags & RADIX_TREE_ITER_TAGGED) ?
1197 !tag_get(node, tag, offset) : !child) {
1198 /* Hole detected */
1199 if (flags & RADIX_TREE_ITER_CONTIG)
1200 return NULL;
1201
1202 if (flags & RADIX_TREE_ITER_TAGGED)
1203 offset = radix_tree_find_next_bit(node, tag,
1204 offset + 1);
1205 else
1206 while (++offset < RADIX_TREE_MAP_SIZE) {
1207 void *slot = rcu_dereference_raw(
1208 node->slots[offset]);
1209 if (slot)
1210 break;
1211 }
1212 index &= ~node_maxindex(node);
1213 index += offset << node->shift;
1214 /* Overflow after ~0UL */
1215 if (!index)
1216 return NULL;
1217 if (offset == RADIX_TREE_MAP_SIZE)
1218 goto restart;
1219 child = rcu_dereference_raw(node->slots[offset]);
1220 }
1221
1222 if (!child)
1223 goto restart;
1224 if (child == RADIX_TREE_RETRY)
1225 break;
1226 } while (node->shift && radix_tree_is_internal_node(child));
1227
1228 /* Update the iterator state */
1229 iter->index = (index &~ node_maxindex(node)) | offset;
1230 iter->next_index = (index | node_maxindex(node)) + 1;
1231 iter->node = node;
1232
1233 if (flags & RADIX_TREE_ITER_TAGGED)
1234 set_iter_tags(iter, node, offset, tag);
1235
1236 return node->slots + offset;
1237}
1238EXPORT_SYMBOL(radix_tree_next_chunk);
1239
1240/**
1241 * radix_tree_gang_lookup - perform multiple lookup on a radix tree
1242 * @root: radix tree root
1243 * @results: where the results of the lookup are placed
1244 * @first_index: start the lookup from this key
1245 * @max_items: place up to this many items at *results
1246 *
1247 * Performs an index-ascending scan of the tree for present items. Places
1248 * them at *@results and returns the number of items which were placed at
1249 * *@results.
1250 *
1251 * The implementation is naive.
1252 *
1253 * Like radix_tree_lookup, radix_tree_gang_lookup may be called under
1254 * rcu_read_lock. In this case, rather than the returned results being
1255 * an atomic snapshot of the tree at a single point in time, the
1256 * semantics of an RCU protected gang lookup are as though multiple
1257 * radix_tree_lookups have been issued in individual locks, and results
1258 * stored in 'results'.
1259 */
1260unsigned int
1261radix_tree_gang_lookup(const struct radix_tree_root *root, void **results,
1262 unsigned long first_index, unsigned int max_items)
1263{
1264 struct radix_tree_iter iter;
1265 void __rcu **slot;
1266 unsigned int ret = 0;
1267
1268 if (unlikely(!max_items))
1269 return 0;
1270
1271 radix_tree_for_each_slot(slot, root, &iter, first_index) {
1272 results[ret] = rcu_dereference_raw(*slot);
1273 if (!results[ret])
1274 continue;
1275 if (radix_tree_is_internal_node(results[ret])) {
1276 slot = radix_tree_iter_retry(&iter);
1277 continue;
1278 }
1279 if (++ret == max_items)
1280 break;
1281 }
1282
1283 return ret;
1284}
1285EXPORT_SYMBOL(radix_tree_gang_lookup);
1286
1287/**
1288 * radix_tree_gang_lookup_tag - perform multiple lookup on a radix tree
1289 * based on a tag
1290 * @root: radix tree root
1291 * @results: where the results of the lookup are placed
1292 * @first_index: start the lookup from this key
1293 * @max_items: place up to this many items at *results
1294 * @tag: the tag index (< RADIX_TREE_MAX_TAGS)
1295 *
1296 * Performs an index-ascending scan of the tree for present items which
1297 * have the tag indexed by @tag set. Places the items at *@results and
1298 * returns the number of items which were placed at *@results.
1299 */
1300unsigned int
1301radix_tree_gang_lookup_tag(const struct radix_tree_root *root, void **results,
1302 unsigned long first_index, unsigned int max_items,
1303 unsigned int tag)
1304{
1305 struct radix_tree_iter iter;
1306 void __rcu **slot;
1307 unsigned int ret = 0;
1308
1309 if (unlikely(!max_items))
1310 return 0;
1311
1312 radix_tree_for_each_tagged(slot, root, &iter, first_index, tag) {
1313 results[ret] = rcu_dereference_raw(*slot);
1314 if (!results[ret])
1315 continue;
1316 if (radix_tree_is_internal_node(results[ret])) {
1317 slot = radix_tree_iter_retry(&iter);
1318 continue;
1319 }
1320 if (++ret == max_items)
1321 break;
1322 }
1323
1324 return ret;
1325}
1326EXPORT_SYMBOL(radix_tree_gang_lookup_tag);
1327
1328/**
1329 * radix_tree_gang_lookup_tag_slot - perform multiple slot lookup on a
1330 * radix tree based on a tag
1331 * @root: radix tree root
1332 * @results: where the results of the lookup are placed
1333 * @first_index: start the lookup from this key
1334 * @max_items: place up to this many items at *results
1335 * @tag: the tag index (< RADIX_TREE_MAX_TAGS)
1336 *
1337 * Performs an index-ascending scan of the tree for present items which
1338 * have the tag indexed by @tag set. Places the slots at *@results and
1339 * returns the number of slots which were placed at *@results.
1340 */
1341unsigned int
1342radix_tree_gang_lookup_tag_slot(const struct radix_tree_root *root,
1343 void __rcu ***results, unsigned long first_index,
1344 unsigned int max_items, unsigned int tag)
1345{
1346 struct radix_tree_iter iter;
1347 void __rcu **slot;
1348 unsigned int ret = 0;
1349
1350 if (unlikely(!max_items))
1351 return 0;
1352
1353 radix_tree_for_each_tagged(slot, root, &iter, first_index, tag) {
1354 results[ret] = slot;
1355 if (++ret == max_items)
1356 break;
1357 }
1358
1359 return ret;
1360}
1361EXPORT_SYMBOL(radix_tree_gang_lookup_tag_slot);
1362
1363static bool __radix_tree_delete(struct radix_tree_root *root,
1364 struct radix_tree_node *node, void __rcu **slot)
1365{
1366 void *old = rcu_dereference_raw(*slot);
1367 int values = xa_is_value(old) ? -1 : 0;
1368 unsigned offset = get_slot_offset(node, slot);
1369 int tag;
1370
1371 if (is_idr(root))
1372 node_tag_set(root, node, IDR_FREE, offset);
1373 else
1374 for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
1375 node_tag_clear(root, node, tag, offset);
1376
1377 replace_slot(slot, NULL, node, -1, values);
1378 return node && delete_node(root, node);
1379}
1380
1381/**
1382 * radix_tree_iter_delete - delete the entry at this iterator position
1383 * @root: radix tree root
1384 * @iter: iterator state
1385 * @slot: pointer to slot
1386 *
1387 * Delete the entry at the position currently pointed to by the iterator.
1388 * This may result in the current node being freed; if it is, the iterator
1389 * is advanced so that it will not reference the freed memory. This
1390 * function may be called without any locking if there are no other threads
1391 * which can access this tree.
1392 */
1393void radix_tree_iter_delete(struct radix_tree_root *root,
1394 struct radix_tree_iter *iter, void __rcu **slot)
1395{
1396 if (__radix_tree_delete(root, iter->node, slot))
1397 iter->index = iter->next_index;
1398}
1399EXPORT_SYMBOL(radix_tree_iter_delete);
1400
1401/**
1402 * radix_tree_delete_item - delete an item from a radix tree
1403 * @root: radix tree root
1404 * @index: index key
1405 * @item: expected item
1406 *
1407 * Remove @item at @index from the radix tree rooted at @root.
1408 *
1409 * Return: the deleted entry, or %NULL if it was not present
1410 * or the entry at the given @index was not @item.
1411 */
1412void *radix_tree_delete_item(struct radix_tree_root *root,
1413 unsigned long index, void *item)
1414{
1415 struct radix_tree_node *node = NULL;
1416 void __rcu **slot = NULL;
1417 void *entry;
1418
1419 entry = __radix_tree_lookup(root, index, &node, &slot);
1420 if (!slot)
1421 return NULL;
1422 if (!entry && (!is_idr(root) || node_tag_get(root, node, IDR_FREE,
1423 get_slot_offset(node, slot))))
1424 return NULL;
1425
1426 if (item && entry != item)
1427 return NULL;
1428
1429 __radix_tree_delete(root, node, slot);
1430
1431 return entry;
1432}
1433EXPORT_SYMBOL(radix_tree_delete_item);
1434
1435/**
1436 * radix_tree_delete - delete an entry from a radix tree
1437 * @root: radix tree root
1438 * @index: index key
1439 *
1440 * Remove the entry at @index from the radix tree rooted at @root.
1441 *
1442 * Return: The deleted entry, or %NULL if it was not present.
1443 */
1444void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
1445{
1446 return radix_tree_delete_item(root, index, NULL);
1447}
1448EXPORT_SYMBOL(radix_tree_delete);
1449
1450/**
1451 * radix_tree_tagged - test whether any items in the tree are tagged
1452 * @root: radix tree root
1453 * @tag: tag to test
1454 */
1455int radix_tree_tagged(const struct radix_tree_root *root, unsigned int tag)
1456{
1457 return root_tag_get(root, tag);
1458}
1459EXPORT_SYMBOL(radix_tree_tagged);
1460
1461/**
1462 * idr_preload - preload for idr_alloc()
1463 * @gfp_mask: allocation mask to use for preloading
1464 *
1465 * Preallocate memory to use for the next call to idr_alloc(). This function
1466 * returns with preemption disabled. It will be enabled by idr_preload_end().
1467 */
1468void idr_preload(gfp_t gfp_mask)
1469{
1470 if (__radix_tree_preload(gfp_mask, IDR_PRELOAD_SIZE))
1471 local_lock(&radix_tree_preloads.lock);
1472}
1473EXPORT_SYMBOL(idr_preload);
1474
1475void __rcu **idr_get_free(struct radix_tree_root *root,
1476 struct radix_tree_iter *iter, gfp_t gfp,
1477 unsigned long max)
1478{
1479 struct radix_tree_node *node = NULL, *child;
1480 void __rcu **slot = (void __rcu **)&root->xa_head;
1481 unsigned long maxindex, start = iter->next_index;
1482 unsigned int shift, offset = 0;
1483
1484 grow:
1485 shift = radix_tree_load_root(root, &child, &maxindex);
1486 if (!radix_tree_tagged(root, IDR_FREE))
1487 start = max(start, maxindex + 1);
1488 if (start > max)
1489 return ERR_PTR(-ENOSPC);
1490
1491 if (start > maxindex) {
1492 int error = radix_tree_extend(root, gfp, start, shift);
1493 if (error < 0)
1494 return ERR_PTR(error);
1495 shift = error;
1496 child = rcu_dereference_raw(root->xa_head);
1497 }
1498 if (start == 0 && shift == 0)
1499 shift = RADIX_TREE_MAP_SHIFT;
1500
1501 while (shift) {
1502 shift -= RADIX_TREE_MAP_SHIFT;
1503 if (child == NULL) {
1504 /* Have to add a child node. */
1505 child = radix_tree_node_alloc(gfp, node, root, shift,
1506 offset, 0, 0);
1507 if (!child)
1508 return ERR_PTR(-ENOMEM);
1509 all_tag_set(child, IDR_FREE);
1510 rcu_assign_pointer(*slot, node_to_entry(child));
1511 if (node)
1512 node->count++;
1513 } else if (!radix_tree_is_internal_node(child))
1514 break;
1515
1516 node = entry_to_node(child);
1517 offset = radix_tree_descend(node, &child, start);
1518 if (!tag_get(node, IDR_FREE, offset)) {
1519 offset = radix_tree_find_next_bit(node, IDR_FREE,
1520 offset + 1);
1521 start = next_index(start, node, offset);
1522 if (start > max || start == 0)
1523 return ERR_PTR(-ENOSPC);
1524 while (offset == RADIX_TREE_MAP_SIZE) {
1525 offset = node->offset + 1;
1526 node = node->parent;
1527 if (!node)
1528 goto grow;
1529 shift = node->shift;
1530 }
1531 child = rcu_dereference_raw(node->slots[offset]);
1532 }
1533 slot = &node->slots[offset];
1534 }
1535
1536 iter->index = start;
1537 if (node)
1538 iter->next_index = 1 + min(max, (start | node_maxindex(node)));
1539 else
1540 iter->next_index = 1;
1541 iter->node = node;
1542 set_iter_tags(iter, node, offset, IDR_FREE);
1543
1544 return slot;
1545}
1546
1547/**
1548 * idr_destroy - release all internal memory from an IDR
1549 * @idr: idr handle
1550 *
1551 * After this function is called, the IDR is empty, and may be reused or
1552 * the data structure containing it may be freed.
1553 *
1554 * A typical clean-up sequence for objects stored in an idr tree will use
1555 * idr_for_each() to free all objects, if necessary, then idr_destroy() to
1556 * free the memory used to keep track of those objects.
1557 */
1558void idr_destroy(struct idr *idr)
1559{
1560 struct radix_tree_node *node = rcu_dereference_raw(idr->idr_rt.xa_head);
1561 if (radix_tree_is_internal_node(node))
1562 radix_tree_free_nodes(node);
1563 idr->idr_rt.xa_head = NULL;
1564 root_tag_set(&idr->idr_rt, IDR_FREE);
1565}
1566EXPORT_SYMBOL(idr_destroy);
1567
1568static void
1569radix_tree_node_ctor(void *arg)
1570{
1571 struct radix_tree_node *node = arg;
1572
1573 memset(node, 0, sizeof(*node));
1574 INIT_LIST_HEAD(&node->private_list);
1575}
1576
1577static int radix_tree_cpu_dead(unsigned int cpu)
1578{
1579 struct radix_tree_preload *rtp;
1580 struct radix_tree_node *node;
1581
1582 /* Free per-cpu pool of preloaded nodes */
1583 rtp = &per_cpu(radix_tree_preloads, cpu);
1584 while (rtp->nr) {
1585 node = rtp->nodes;
1586 rtp->nodes = node->parent;
1587 kmem_cache_free(radix_tree_node_cachep, node);
1588 rtp->nr--;
1589 }
1590 return 0;
1591}
1592
1593void __init radix_tree_init(void)
1594{
1595 int ret;
1596
1597 BUILD_BUG_ON(RADIX_TREE_MAX_TAGS + __GFP_BITS_SHIFT > 32);
1598 BUILD_BUG_ON(ROOT_IS_IDR & ~GFP_ZONEMASK);
1599 BUILD_BUG_ON(XA_CHUNK_SIZE > 255);
1600 radix_tree_node_cachep = kmem_cache_create("radix_tree_node",
1601 sizeof(struct radix_tree_node), 0,
1602 SLAB_PANIC | SLAB_RECLAIM_ACCOUNT,
1603 radix_tree_node_ctor);
1604 ret = cpuhp_setup_state_nocalls(CPUHP_RADIX_DEAD, "lib/radix:dead",
1605 NULL, radix_tree_cpu_dead);
1606 WARN_ON(ret < 0);
1607}
1/*
2 * Copyright (C) 2001 Momchil Velikov
3 * Portions Copyright (C) 2001 Christoph Hellwig
4 * Copyright (C) 2005 SGI, Christoph Lameter
5 * Copyright (C) 2006 Nick Piggin
6 * Copyright (C) 2012 Konstantin Khlebnikov
7 * Copyright (C) 2016 Intel, Matthew Wilcox
8 * Copyright (C) 2016 Intel, Ross Zwisler
9 *
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public License as
12 * published by the Free Software Foundation; either version 2, or (at
13 * your option) any later version.
14 *
15 * This program is distributed in the hope that it will be useful, but
16 * WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18 * General Public License for more details.
19 *
20 * You should have received a copy of the GNU General Public License
21 * along with this program; if not, write to the Free Software
22 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
23 */
24
25#include <linux/bitmap.h>
26#include <linux/bitops.h>
27#include <linux/bug.h>
28#include <linux/cpu.h>
29#include <linux/errno.h>
30#include <linux/export.h>
31#include <linux/idr.h>
32#include <linux/init.h>
33#include <linux/kernel.h>
34#include <linux/kmemleak.h>
35#include <linux/percpu.h>
36#include <linux/preempt.h> /* in_interrupt() */
37#include <linux/radix-tree.h>
38#include <linux/rcupdate.h>
39#include <linux/slab.h>
40#include <linux/string.h>
41
42
43/* Number of nodes in fully populated tree of given height */
44static unsigned long height_to_maxnodes[RADIX_TREE_MAX_PATH + 1] __read_mostly;
45
46/*
47 * Radix tree node cache.
48 */
49static struct kmem_cache *radix_tree_node_cachep;
50
51/*
52 * The radix tree is variable-height, so an insert operation not only has
53 * to build the branch to its corresponding item, it also has to build the
54 * branch to existing items if the size has to be increased (by
55 * radix_tree_extend).
56 *
57 * The worst case is a zero height tree with just a single item at index 0,
58 * and then inserting an item at index ULONG_MAX. This requires 2 new branches
59 * of RADIX_TREE_MAX_PATH size to be created, with only the root node shared.
60 * Hence:
61 */
62#define RADIX_TREE_PRELOAD_SIZE (RADIX_TREE_MAX_PATH * 2 - 1)
63
64/*
65 * The IDR does not have to be as high as the radix tree since it uses
66 * signed integers, not unsigned longs.
67 */
68#define IDR_INDEX_BITS (8 /* CHAR_BIT */ * sizeof(int) - 1)
69#define IDR_MAX_PATH (DIV_ROUND_UP(IDR_INDEX_BITS, \
70 RADIX_TREE_MAP_SHIFT))
71#define IDR_PRELOAD_SIZE (IDR_MAX_PATH * 2 - 1)
72
73/*
74 * The IDA is even shorter since it uses a bitmap at the last level.
75 */
76#define IDA_INDEX_BITS (8 * sizeof(int) - 1 - ilog2(IDA_BITMAP_BITS))
77#define IDA_MAX_PATH (DIV_ROUND_UP(IDA_INDEX_BITS, \
78 RADIX_TREE_MAP_SHIFT))
79#define IDA_PRELOAD_SIZE (IDA_MAX_PATH * 2 - 1)
80
81/*
82 * Per-cpu pool of preloaded nodes
83 */
84struct radix_tree_preload {
85 unsigned nr;
86 /* nodes->parent points to next preallocated node */
87 struct radix_tree_node *nodes;
88};
89static DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = { 0, };
90
91static inline struct radix_tree_node *entry_to_node(void *ptr)
92{
93 return (void *)((unsigned long)ptr & ~RADIX_TREE_INTERNAL_NODE);
94}
95
96static inline void *node_to_entry(void *ptr)
97{
98 return (void *)((unsigned long)ptr | RADIX_TREE_INTERNAL_NODE);
99}
100
101#define RADIX_TREE_RETRY node_to_entry(NULL)
102
103#ifdef CONFIG_RADIX_TREE_MULTIORDER
104/* Sibling slots point directly to another slot in the same node */
105static inline
106bool is_sibling_entry(const struct radix_tree_node *parent, void *node)
107{
108 void __rcu **ptr = node;
109 return (parent->slots <= ptr) &&
110 (ptr < parent->slots + RADIX_TREE_MAP_SIZE);
111}
112#else
113static inline
114bool is_sibling_entry(const struct radix_tree_node *parent, void *node)
115{
116 return false;
117}
118#endif
119
120static inline unsigned long
121get_slot_offset(const struct radix_tree_node *parent, void __rcu **slot)
122{
123 return slot - parent->slots;
124}
125
126static unsigned int radix_tree_descend(const struct radix_tree_node *parent,
127 struct radix_tree_node **nodep, unsigned long index)
128{
129 unsigned int offset = (index >> parent->shift) & RADIX_TREE_MAP_MASK;
130 void __rcu **entry = rcu_dereference_raw(parent->slots[offset]);
131
132#ifdef CONFIG_RADIX_TREE_MULTIORDER
133 if (radix_tree_is_internal_node(entry)) {
134 if (is_sibling_entry(parent, entry)) {
135 void __rcu **sibentry;
136 sibentry = (void __rcu **) entry_to_node(entry);
137 offset = get_slot_offset(parent, sibentry);
138 entry = rcu_dereference_raw(*sibentry);
139 }
140 }
141#endif
142
143 *nodep = (void *)entry;
144 return offset;
145}
146
147static inline gfp_t root_gfp_mask(const struct radix_tree_root *root)
148{
149 return root->gfp_mask & (__GFP_BITS_MASK & ~GFP_ZONEMASK);
150}
151
152static inline void tag_set(struct radix_tree_node *node, unsigned int tag,
153 int offset)
154{
155 __set_bit(offset, node->tags[tag]);
156}
157
158static inline void tag_clear(struct radix_tree_node *node, unsigned int tag,
159 int offset)
160{
161 __clear_bit(offset, node->tags[tag]);
162}
163
164static inline int tag_get(const struct radix_tree_node *node, unsigned int tag,
165 int offset)
166{
167 return test_bit(offset, node->tags[tag]);
168}
169
170static inline void root_tag_set(struct radix_tree_root *root, unsigned tag)
171{
172 root->gfp_mask |= (__force gfp_t)(1 << (tag + ROOT_TAG_SHIFT));
173}
174
175static inline void root_tag_clear(struct radix_tree_root *root, unsigned tag)
176{
177 root->gfp_mask &= (__force gfp_t)~(1 << (tag + ROOT_TAG_SHIFT));
178}
179
180static inline void root_tag_clear_all(struct radix_tree_root *root)
181{
182 root->gfp_mask &= (1 << ROOT_TAG_SHIFT) - 1;
183}
184
185static inline int root_tag_get(const struct radix_tree_root *root, unsigned tag)
186{
187 return (__force int)root->gfp_mask & (1 << (tag + ROOT_TAG_SHIFT));
188}
189
190static inline unsigned root_tags_get(const struct radix_tree_root *root)
191{
192 return (__force unsigned)root->gfp_mask >> ROOT_TAG_SHIFT;
193}
194
195static inline bool is_idr(const struct radix_tree_root *root)
196{
197 return !!(root->gfp_mask & ROOT_IS_IDR);
198}
199
200/*
201 * Returns 1 if any slot in the node has this tag set.
202 * Otherwise returns 0.
203 */
204static inline int any_tag_set(const struct radix_tree_node *node,
205 unsigned int tag)
206{
207 unsigned idx;
208 for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) {
209 if (node->tags[tag][idx])
210 return 1;
211 }
212 return 0;
213}
214
215static inline void all_tag_set(struct radix_tree_node *node, unsigned int tag)
216{
217 bitmap_fill(node->tags[tag], RADIX_TREE_MAP_SIZE);
218}
219
220/**
221 * radix_tree_find_next_bit - find the next set bit in a memory region
222 *
223 * @addr: The address to base the search on
224 * @size: The bitmap size in bits
225 * @offset: The bitnumber to start searching at
226 *
227 * Unrollable variant of find_next_bit() for constant size arrays.
228 * Tail bits starting from size to roundup(size, BITS_PER_LONG) must be zero.
229 * Returns next bit offset, or size if nothing found.
230 */
231static __always_inline unsigned long
232radix_tree_find_next_bit(struct radix_tree_node *node, unsigned int tag,
233 unsigned long offset)
234{
235 const unsigned long *addr = node->tags[tag];
236
237 if (offset < RADIX_TREE_MAP_SIZE) {
238 unsigned long tmp;
239
240 addr += offset / BITS_PER_LONG;
241 tmp = *addr >> (offset % BITS_PER_LONG);
242 if (tmp)
243 return __ffs(tmp) + offset;
244 offset = (offset + BITS_PER_LONG) & ~(BITS_PER_LONG - 1);
245 while (offset < RADIX_TREE_MAP_SIZE) {
246 tmp = *++addr;
247 if (tmp)
248 return __ffs(tmp) + offset;
249 offset += BITS_PER_LONG;
250 }
251 }
252 return RADIX_TREE_MAP_SIZE;
253}
254
255static unsigned int iter_offset(const struct radix_tree_iter *iter)
256{
257 return (iter->index >> iter_shift(iter)) & RADIX_TREE_MAP_MASK;
258}
259
260/*
261 * The maximum index which can be stored in a radix tree
262 */
263static inline unsigned long shift_maxindex(unsigned int shift)
264{
265 return (RADIX_TREE_MAP_SIZE << shift) - 1;
266}
267
268static inline unsigned long node_maxindex(const struct radix_tree_node *node)
269{
270 return shift_maxindex(node->shift);
271}
272
273static unsigned long next_index(unsigned long index,
274 const struct radix_tree_node *node,
275 unsigned long offset)
276{
277 return (index & ~node_maxindex(node)) + (offset << node->shift);
278}
279
280#ifndef __KERNEL__
281static void dump_node(struct radix_tree_node *node, unsigned long index)
282{
283 unsigned long i;
284
285 pr_debug("radix node: %p offset %d indices %lu-%lu parent %p tags %lx %lx %lx shift %d count %d exceptional %d\n",
286 node, node->offset, index, index | node_maxindex(node),
287 node->parent,
288 node->tags[0][0], node->tags[1][0], node->tags[2][0],
289 node->shift, node->count, node->exceptional);
290
291 for (i = 0; i < RADIX_TREE_MAP_SIZE; i++) {
292 unsigned long first = index | (i << node->shift);
293 unsigned long last = first | ((1UL << node->shift) - 1);
294 void *entry = node->slots[i];
295 if (!entry)
296 continue;
297 if (entry == RADIX_TREE_RETRY) {
298 pr_debug("radix retry offset %ld indices %lu-%lu parent %p\n",
299 i, first, last, node);
300 } else if (!radix_tree_is_internal_node(entry)) {
301 pr_debug("radix entry %p offset %ld indices %lu-%lu parent %p\n",
302 entry, i, first, last, node);
303 } else if (is_sibling_entry(node, entry)) {
304 pr_debug("radix sblng %p offset %ld indices %lu-%lu parent %p val %p\n",
305 entry, i, first, last, node,
306 *(void **)entry_to_node(entry));
307 } else {
308 dump_node(entry_to_node(entry), first);
309 }
310 }
311}
312
313/* For debug */
314static void radix_tree_dump(struct radix_tree_root *root)
315{
316 pr_debug("radix root: %p rnode %p tags %x\n",
317 root, root->rnode,
318 root->gfp_mask >> ROOT_TAG_SHIFT);
319 if (!radix_tree_is_internal_node(root->rnode))
320 return;
321 dump_node(entry_to_node(root->rnode), 0);
322}
323
324static void dump_ida_node(void *entry, unsigned long index)
325{
326 unsigned long i;
327
328 if (!entry)
329 return;
330
331 if (radix_tree_is_internal_node(entry)) {
332 struct radix_tree_node *node = entry_to_node(entry);
333
334 pr_debug("ida node: %p offset %d indices %lu-%lu parent %p free %lx shift %d count %d\n",
335 node, node->offset, index * IDA_BITMAP_BITS,
336 ((index | node_maxindex(node)) + 1) *
337 IDA_BITMAP_BITS - 1,
338 node->parent, node->tags[0][0], node->shift,
339 node->count);
340 for (i = 0; i < RADIX_TREE_MAP_SIZE; i++)
341 dump_ida_node(node->slots[i],
342 index | (i << node->shift));
343 } else if (radix_tree_exceptional_entry(entry)) {
344 pr_debug("ida excp: %p offset %d indices %lu-%lu data %lx\n",
345 entry, (int)(index & RADIX_TREE_MAP_MASK),
346 index * IDA_BITMAP_BITS,
347 index * IDA_BITMAP_BITS + BITS_PER_LONG -
348 RADIX_TREE_EXCEPTIONAL_SHIFT,
349 (unsigned long)entry >>
350 RADIX_TREE_EXCEPTIONAL_SHIFT);
351 } else {
352 struct ida_bitmap *bitmap = entry;
353
354 pr_debug("ida btmp: %p offset %d indices %lu-%lu data", bitmap,
355 (int)(index & RADIX_TREE_MAP_MASK),
356 index * IDA_BITMAP_BITS,
357 (index + 1) * IDA_BITMAP_BITS - 1);
358 for (i = 0; i < IDA_BITMAP_LONGS; i++)
359 pr_cont(" %lx", bitmap->bitmap[i]);
360 pr_cont("\n");
361 }
362}
363
364static void ida_dump(struct ida *ida)
365{
366 struct radix_tree_root *root = &ida->ida_rt;
367 pr_debug("ida: %p node %p free %d\n", ida, root->rnode,
368 root->gfp_mask >> ROOT_TAG_SHIFT);
369 dump_ida_node(root->rnode, 0);
370}
371#endif
372
373/*
374 * This assumes that the caller has performed appropriate preallocation, and
375 * that the caller has pinned this thread of control to the current CPU.
376 */
377static struct radix_tree_node *
378radix_tree_node_alloc(gfp_t gfp_mask, struct radix_tree_node *parent,
379 struct radix_tree_root *root,
380 unsigned int shift, unsigned int offset,
381 unsigned int count, unsigned int exceptional)
382{
383 struct radix_tree_node *ret = NULL;
384
385 /*
386 * Preload code isn't irq safe and it doesn't make sense to use
387 * preloading during an interrupt anyway as all the allocations have
388 * to be atomic. So just do normal allocation when in interrupt.
389 */
390 if (!gfpflags_allow_blocking(gfp_mask) && !in_interrupt()) {
391 struct radix_tree_preload *rtp;
392
393 /*
394 * Even if the caller has preloaded, try to allocate from the
395 * cache first for the new node to get accounted to the memory
396 * cgroup.
397 */
398 ret = kmem_cache_alloc(radix_tree_node_cachep,
399 gfp_mask | __GFP_NOWARN);
400 if (ret)
401 goto out;
402
403 /*
404 * Provided the caller has preloaded here, we will always
405 * succeed in getting a node here (and never reach
406 * kmem_cache_alloc)
407 */
408 rtp = this_cpu_ptr(&radix_tree_preloads);
409 if (rtp->nr) {
410 ret = rtp->nodes;
411 rtp->nodes = ret->parent;
412 rtp->nr--;
413 }
414 /*
415 * Update the allocation stack trace as this is more useful
416 * for debugging.
417 */
418 kmemleak_update_trace(ret);
419 goto out;
420 }
421 ret = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask);
422out:
423 BUG_ON(radix_tree_is_internal_node(ret));
424 if (ret) {
425 ret->shift = shift;
426 ret->offset = offset;
427 ret->count = count;
428 ret->exceptional = exceptional;
429 ret->parent = parent;
430 ret->root = root;
431 }
432 return ret;
433}
434
435static void radix_tree_node_rcu_free(struct rcu_head *head)
436{
437 struct radix_tree_node *node =
438 container_of(head, struct radix_tree_node, rcu_head);
439
440 /*
441 * Must only free zeroed nodes into the slab. We can be left with
442 * non-NULL entries by radix_tree_free_nodes, so clear the entries
443 * and tags here.
444 */
445 memset(node->slots, 0, sizeof(node->slots));
446 memset(node->tags, 0, sizeof(node->tags));
447 INIT_LIST_HEAD(&node->private_list);
448
449 kmem_cache_free(radix_tree_node_cachep, node);
450}
451
452static inline void
453radix_tree_node_free(struct radix_tree_node *node)
454{
455 call_rcu(&node->rcu_head, radix_tree_node_rcu_free);
456}
457
458/*
459 * Load up this CPU's radix_tree_node buffer with sufficient objects to
460 * ensure that the addition of a single element in the tree cannot fail. On
461 * success, return zero, with preemption disabled. On error, return -ENOMEM
462 * with preemption not disabled.
463 *
464 * To make use of this facility, the radix tree must be initialised without
465 * __GFP_DIRECT_RECLAIM being passed to INIT_RADIX_TREE().
466 */
467static __must_check int __radix_tree_preload(gfp_t gfp_mask, unsigned nr)
468{
469 struct radix_tree_preload *rtp;
470 struct radix_tree_node *node;
471 int ret = -ENOMEM;
472
473 /*
474 * Nodes preloaded by one cgroup can be be used by another cgroup, so
475 * they should never be accounted to any particular memory cgroup.
476 */
477 gfp_mask &= ~__GFP_ACCOUNT;
478
479 preempt_disable();
480 rtp = this_cpu_ptr(&radix_tree_preloads);
481 while (rtp->nr < nr) {
482 preempt_enable();
483 node = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask);
484 if (node == NULL)
485 goto out;
486 preempt_disable();
487 rtp = this_cpu_ptr(&radix_tree_preloads);
488 if (rtp->nr < nr) {
489 node->parent = rtp->nodes;
490 rtp->nodes = node;
491 rtp->nr++;
492 } else {
493 kmem_cache_free(radix_tree_node_cachep, node);
494 }
495 }
496 ret = 0;
497out:
498 return ret;
499}
500
501/*
502 * Load up this CPU's radix_tree_node buffer with sufficient objects to
503 * ensure that the addition of a single element in the tree cannot fail. On
504 * success, return zero, with preemption disabled. On error, return -ENOMEM
505 * with preemption not disabled.
506 *
507 * To make use of this facility, the radix tree must be initialised without
508 * __GFP_DIRECT_RECLAIM being passed to INIT_RADIX_TREE().
509 */
510int radix_tree_preload(gfp_t gfp_mask)
511{
512 /* Warn on non-sensical use... */
513 WARN_ON_ONCE(!gfpflags_allow_blocking(gfp_mask));
514 return __radix_tree_preload(gfp_mask, RADIX_TREE_PRELOAD_SIZE);
515}
516EXPORT_SYMBOL(radix_tree_preload);
517
518/*
519 * The same as above function, except we don't guarantee preloading happens.
520 * We do it, if we decide it helps. On success, return zero with preemption
521 * disabled. On error, return -ENOMEM with preemption not disabled.
522 */
523int radix_tree_maybe_preload(gfp_t gfp_mask)
524{
525 if (gfpflags_allow_blocking(gfp_mask))
526 return __radix_tree_preload(gfp_mask, RADIX_TREE_PRELOAD_SIZE);
527 /* Preloading doesn't help anything with this gfp mask, skip it */
528 preempt_disable();
529 return 0;
530}
531EXPORT_SYMBOL(radix_tree_maybe_preload);
532
533#ifdef CONFIG_RADIX_TREE_MULTIORDER
534/*
535 * Preload with enough objects to ensure that we can split a single entry
536 * of order @old_order into many entries of size @new_order
537 */
538int radix_tree_split_preload(unsigned int old_order, unsigned int new_order,
539 gfp_t gfp_mask)
540{
541 unsigned top = 1 << (old_order % RADIX_TREE_MAP_SHIFT);
542 unsigned layers = (old_order / RADIX_TREE_MAP_SHIFT) -
543 (new_order / RADIX_TREE_MAP_SHIFT);
544 unsigned nr = 0;
545
546 WARN_ON_ONCE(!gfpflags_allow_blocking(gfp_mask));
547 BUG_ON(new_order >= old_order);
548
549 while (layers--)
550 nr = nr * RADIX_TREE_MAP_SIZE + 1;
551 return __radix_tree_preload(gfp_mask, top * nr);
552}
553#endif
554
555/*
556 * The same as function above, but preload number of nodes required to insert
557 * (1 << order) continuous naturally-aligned elements.
558 */
559int radix_tree_maybe_preload_order(gfp_t gfp_mask, int order)
560{
561 unsigned long nr_subtrees;
562 int nr_nodes, subtree_height;
563
564 /* Preloading doesn't help anything with this gfp mask, skip it */
565 if (!gfpflags_allow_blocking(gfp_mask)) {
566 preempt_disable();
567 return 0;
568 }
569
570 /*
571 * Calculate number and height of fully populated subtrees it takes to
572 * store (1 << order) elements.
573 */
574 nr_subtrees = 1 << order;
575 for (subtree_height = 0; nr_subtrees > RADIX_TREE_MAP_SIZE;
576 subtree_height++)
577 nr_subtrees >>= RADIX_TREE_MAP_SHIFT;
578
579 /*
580 * The worst case is zero height tree with a single item at index 0 and
581 * then inserting items starting at ULONG_MAX - (1 << order).
582 *
583 * This requires RADIX_TREE_MAX_PATH nodes to build branch from root to
584 * 0-index item.
585 */
586 nr_nodes = RADIX_TREE_MAX_PATH;
587
588 /* Plus branch to fully populated subtrees. */
589 nr_nodes += RADIX_TREE_MAX_PATH - subtree_height;
590
591 /* Root node is shared. */
592 nr_nodes--;
593
594 /* Plus nodes required to build subtrees. */
595 nr_nodes += nr_subtrees * height_to_maxnodes[subtree_height];
596
597 return __radix_tree_preload(gfp_mask, nr_nodes);
598}
599
600static unsigned radix_tree_load_root(const struct radix_tree_root *root,
601 struct radix_tree_node **nodep, unsigned long *maxindex)
602{
603 struct radix_tree_node *node = rcu_dereference_raw(root->rnode);
604
605 *nodep = node;
606
607 if (likely(radix_tree_is_internal_node(node))) {
608 node = entry_to_node(node);
609 *maxindex = node_maxindex(node);
610 return node->shift + RADIX_TREE_MAP_SHIFT;
611 }
612
613 *maxindex = 0;
614 return 0;
615}
616
617/*
618 * Extend a radix tree so it can store key @index.
619 */
620static int radix_tree_extend(struct radix_tree_root *root, gfp_t gfp,
621 unsigned long index, unsigned int shift)
622{
623 void *entry;
624 unsigned int maxshift;
625 int tag;
626
627 /* Figure out what the shift should be. */
628 maxshift = shift;
629 while (index > shift_maxindex(maxshift))
630 maxshift += RADIX_TREE_MAP_SHIFT;
631
632 entry = rcu_dereference_raw(root->rnode);
633 if (!entry && (!is_idr(root) || root_tag_get(root, IDR_FREE)))
634 goto out;
635
636 do {
637 struct radix_tree_node *node = radix_tree_node_alloc(gfp, NULL,
638 root, shift, 0, 1, 0);
639 if (!node)
640 return -ENOMEM;
641
642 if (is_idr(root)) {
643 all_tag_set(node, IDR_FREE);
644 if (!root_tag_get(root, IDR_FREE)) {
645 tag_clear(node, IDR_FREE, 0);
646 root_tag_set(root, IDR_FREE);
647 }
648 } else {
649 /* Propagate the aggregated tag info to the new child */
650 for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
651 if (root_tag_get(root, tag))
652 tag_set(node, tag, 0);
653 }
654 }
655
656 BUG_ON(shift > BITS_PER_LONG);
657 if (radix_tree_is_internal_node(entry)) {
658 entry_to_node(entry)->parent = node;
659 } else if (radix_tree_exceptional_entry(entry)) {
660 /* Moving an exceptional root->rnode to a node */
661 node->exceptional = 1;
662 }
663 /*
664 * entry was already in the radix tree, so we do not need
665 * rcu_assign_pointer here
666 */
667 node->slots[0] = (void __rcu *)entry;
668 entry = node_to_entry(node);
669 rcu_assign_pointer(root->rnode, entry);
670 shift += RADIX_TREE_MAP_SHIFT;
671 } while (shift <= maxshift);
672out:
673 return maxshift + RADIX_TREE_MAP_SHIFT;
674}
675
676/**
677 * radix_tree_shrink - shrink radix tree to minimum height
678 * @root radix tree root
679 */
680static inline bool radix_tree_shrink(struct radix_tree_root *root,
681 radix_tree_update_node_t update_node)
682{
683 bool shrunk = false;
684
685 for (;;) {
686 struct radix_tree_node *node = rcu_dereference_raw(root->rnode);
687 struct radix_tree_node *child;
688
689 if (!radix_tree_is_internal_node(node))
690 break;
691 node = entry_to_node(node);
692
693 /*
694 * The candidate node has more than one child, or its child
695 * is not at the leftmost slot, or the child is a multiorder
696 * entry, we cannot shrink.
697 */
698 if (node->count != 1)
699 break;
700 child = rcu_dereference_raw(node->slots[0]);
701 if (!child)
702 break;
703 if (!radix_tree_is_internal_node(child) && node->shift)
704 break;
705
706 if (radix_tree_is_internal_node(child))
707 entry_to_node(child)->parent = NULL;
708
709 /*
710 * We don't need rcu_assign_pointer(), since we are simply
711 * moving the node from one part of the tree to another: if it
712 * was safe to dereference the old pointer to it
713 * (node->slots[0]), it will be safe to dereference the new
714 * one (root->rnode) as far as dependent read barriers go.
715 */
716 root->rnode = (void __rcu *)child;
717 if (is_idr(root) && !tag_get(node, IDR_FREE, 0))
718 root_tag_clear(root, IDR_FREE);
719
720 /*
721 * We have a dilemma here. The node's slot[0] must not be
722 * NULLed in case there are concurrent lookups expecting to
723 * find the item. However if this was a bottom-level node,
724 * then it may be subject to the slot pointer being visible
725 * to callers dereferencing it. If item corresponding to
726 * slot[0] is subsequently deleted, these callers would expect
727 * their slot to become empty sooner or later.
728 *
729 * For example, lockless pagecache will look up a slot, deref
730 * the page pointer, and if the page has 0 refcount it means it
731 * was concurrently deleted from pagecache so try the deref
732 * again. Fortunately there is already a requirement for logic
733 * to retry the entire slot lookup -- the indirect pointer
734 * problem (replacing direct root node with an indirect pointer
735 * also results in a stale slot). So tag the slot as indirect
736 * to force callers to retry.
737 */
738 node->count = 0;
739 if (!radix_tree_is_internal_node(child)) {
740 node->slots[0] = (void __rcu *)RADIX_TREE_RETRY;
741 if (update_node)
742 update_node(node);
743 }
744
745 WARN_ON_ONCE(!list_empty(&node->private_list));
746 radix_tree_node_free(node);
747 shrunk = true;
748 }
749
750 return shrunk;
751}
752
753static bool delete_node(struct radix_tree_root *root,
754 struct radix_tree_node *node,
755 radix_tree_update_node_t update_node)
756{
757 bool deleted = false;
758
759 do {
760 struct radix_tree_node *parent;
761
762 if (node->count) {
763 if (node_to_entry(node) ==
764 rcu_dereference_raw(root->rnode))
765 deleted |= radix_tree_shrink(root,
766 update_node);
767 return deleted;
768 }
769
770 parent = node->parent;
771 if (parent) {
772 parent->slots[node->offset] = NULL;
773 parent->count--;
774 } else {
775 /*
776 * Shouldn't the tags already have all been cleared
777 * by the caller?
778 */
779 if (!is_idr(root))
780 root_tag_clear_all(root);
781 root->rnode = NULL;
782 }
783
784 WARN_ON_ONCE(!list_empty(&node->private_list));
785 radix_tree_node_free(node);
786 deleted = true;
787
788 node = parent;
789 } while (node);
790
791 return deleted;
792}
793
794/**
795 * __radix_tree_create - create a slot in a radix tree
796 * @root: radix tree root
797 * @index: index key
798 * @order: index occupies 2^order aligned slots
799 * @nodep: returns node
800 * @slotp: returns slot
801 *
802 * Create, if necessary, and return the node and slot for an item
803 * at position @index in the radix tree @root.
804 *
805 * Until there is more than one item in the tree, no nodes are
806 * allocated and @root->rnode is used as a direct slot instead of
807 * pointing to a node, in which case *@nodep will be NULL.
808 *
809 * Returns -ENOMEM, or 0 for success.
810 */
811int __radix_tree_create(struct radix_tree_root *root, unsigned long index,
812 unsigned order, struct radix_tree_node **nodep,
813 void __rcu ***slotp)
814{
815 struct radix_tree_node *node = NULL, *child;
816 void __rcu **slot = (void __rcu **)&root->rnode;
817 unsigned long maxindex;
818 unsigned int shift, offset = 0;
819 unsigned long max = index | ((1UL << order) - 1);
820 gfp_t gfp = root_gfp_mask(root);
821
822 shift = radix_tree_load_root(root, &child, &maxindex);
823
824 /* Make sure the tree is high enough. */
825 if (order > 0 && max == ((1UL << order) - 1))
826 max++;
827 if (max > maxindex) {
828 int error = radix_tree_extend(root, gfp, max, shift);
829 if (error < 0)
830 return error;
831 shift = error;
832 child = rcu_dereference_raw(root->rnode);
833 }
834
835 while (shift > order) {
836 shift -= RADIX_TREE_MAP_SHIFT;
837 if (child == NULL) {
838 /* Have to add a child node. */
839 child = radix_tree_node_alloc(gfp, node, root, shift,
840 offset, 0, 0);
841 if (!child)
842 return -ENOMEM;
843 rcu_assign_pointer(*slot, node_to_entry(child));
844 if (node)
845 node->count++;
846 } else if (!radix_tree_is_internal_node(child))
847 break;
848
849 /* Go a level down */
850 node = entry_to_node(child);
851 offset = radix_tree_descend(node, &child, index);
852 slot = &node->slots[offset];
853 }
854
855 if (nodep)
856 *nodep = node;
857 if (slotp)
858 *slotp = slot;
859 return 0;
860}
861
862/*
863 * Free any nodes below this node. The tree is presumed to not need
864 * shrinking, and any user data in the tree is presumed to not need a
865 * destructor called on it. If we need to add a destructor, we can
866 * add that functionality later. Note that we may not clear tags or
867 * slots from the tree as an RCU walker may still have a pointer into
868 * this subtree. We could replace the entries with RADIX_TREE_RETRY,
869 * but we'll still have to clear those in rcu_free.
870 */
871static void radix_tree_free_nodes(struct radix_tree_node *node)
872{
873 unsigned offset = 0;
874 struct radix_tree_node *child = entry_to_node(node);
875
876 for (;;) {
877 void *entry = rcu_dereference_raw(child->slots[offset]);
878 if (radix_tree_is_internal_node(entry) &&
879 !is_sibling_entry(child, entry)) {
880 child = entry_to_node(entry);
881 offset = 0;
882 continue;
883 }
884 offset++;
885 while (offset == RADIX_TREE_MAP_SIZE) {
886 struct radix_tree_node *old = child;
887 offset = child->offset + 1;
888 child = child->parent;
889 WARN_ON_ONCE(!list_empty(&old->private_list));
890 radix_tree_node_free(old);
891 if (old == entry_to_node(node))
892 return;
893 }
894 }
895}
896
897#ifdef CONFIG_RADIX_TREE_MULTIORDER
898static inline int insert_entries(struct radix_tree_node *node,
899 void __rcu **slot, void *item, unsigned order, bool replace)
900{
901 struct radix_tree_node *child;
902 unsigned i, n, tag, offset, tags = 0;
903
904 if (node) {
905 if (order > node->shift)
906 n = 1 << (order - node->shift);
907 else
908 n = 1;
909 offset = get_slot_offset(node, slot);
910 } else {
911 n = 1;
912 offset = 0;
913 }
914
915 if (n > 1) {
916 offset = offset & ~(n - 1);
917 slot = &node->slots[offset];
918 }
919 child = node_to_entry(slot);
920
921 for (i = 0; i < n; i++) {
922 if (slot[i]) {
923 if (replace) {
924 node->count--;
925 for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
926 if (tag_get(node, tag, offset + i))
927 tags |= 1 << tag;
928 } else
929 return -EEXIST;
930 }
931 }
932
933 for (i = 0; i < n; i++) {
934 struct radix_tree_node *old = rcu_dereference_raw(slot[i]);
935 if (i) {
936 rcu_assign_pointer(slot[i], child);
937 for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
938 if (tags & (1 << tag))
939 tag_clear(node, tag, offset + i);
940 } else {
941 rcu_assign_pointer(slot[i], item);
942 for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
943 if (tags & (1 << tag))
944 tag_set(node, tag, offset);
945 }
946 if (radix_tree_is_internal_node(old) &&
947 !is_sibling_entry(node, old) &&
948 (old != RADIX_TREE_RETRY))
949 radix_tree_free_nodes(old);
950 if (radix_tree_exceptional_entry(old))
951 node->exceptional--;
952 }
953 if (node) {
954 node->count += n;
955 if (radix_tree_exceptional_entry(item))
956 node->exceptional += n;
957 }
958 return n;
959}
960#else
961static inline int insert_entries(struct radix_tree_node *node,
962 void __rcu **slot, void *item, unsigned order, bool replace)
963{
964 if (*slot)
965 return -EEXIST;
966 rcu_assign_pointer(*slot, item);
967 if (node) {
968 node->count++;
969 if (radix_tree_exceptional_entry(item))
970 node->exceptional++;
971 }
972 return 1;
973}
974#endif
975
976/**
977 * __radix_tree_insert - insert into a radix tree
978 * @root: radix tree root
979 * @index: index key
980 * @order: key covers the 2^order indices around index
981 * @item: item to insert
982 *
983 * Insert an item into the radix tree at position @index.
984 */
985int __radix_tree_insert(struct radix_tree_root *root, unsigned long index,
986 unsigned order, void *item)
987{
988 struct radix_tree_node *node;
989 void __rcu **slot;
990 int error;
991
992 BUG_ON(radix_tree_is_internal_node(item));
993
994 error = __radix_tree_create(root, index, order, &node, &slot);
995 if (error)
996 return error;
997
998 error = insert_entries(node, slot, item, order, false);
999 if (error < 0)
1000 return error;
1001
1002 if (node) {
1003 unsigned offset = get_slot_offset(node, slot);
1004 BUG_ON(tag_get(node, 0, offset));
1005 BUG_ON(tag_get(node, 1, offset));
1006 BUG_ON(tag_get(node, 2, offset));
1007 } else {
1008 BUG_ON(root_tags_get(root));
1009 }
1010
1011 return 0;
1012}
1013EXPORT_SYMBOL(__radix_tree_insert);
1014
1015/**
1016 * __radix_tree_lookup - lookup an item in a radix tree
1017 * @root: radix tree root
1018 * @index: index key
1019 * @nodep: returns node
1020 * @slotp: returns slot
1021 *
1022 * Lookup and return the item at position @index in the radix
1023 * tree @root.
1024 *
1025 * Until there is more than one item in the tree, no nodes are
1026 * allocated and @root->rnode is used as a direct slot instead of
1027 * pointing to a node, in which case *@nodep will be NULL.
1028 */
1029void *__radix_tree_lookup(const struct radix_tree_root *root,
1030 unsigned long index, struct radix_tree_node **nodep,
1031 void __rcu ***slotp)
1032{
1033 struct radix_tree_node *node, *parent;
1034 unsigned long maxindex;
1035 void __rcu **slot;
1036
1037 restart:
1038 parent = NULL;
1039 slot = (void __rcu **)&root->rnode;
1040 radix_tree_load_root(root, &node, &maxindex);
1041 if (index > maxindex)
1042 return NULL;
1043
1044 while (radix_tree_is_internal_node(node)) {
1045 unsigned offset;
1046
1047 if (node == RADIX_TREE_RETRY)
1048 goto restart;
1049 parent = entry_to_node(node);
1050 offset = radix_tree_descend(parent, &node, index);
1051 slot = parent->slots + offset;
1052 }
1053
1054 if (nodep)
1055 *nodep = parent;
1056 if (slotp)
1057 *slotp = slot;
1058 return node;
1059}
1060
1061/**
1062 * radix_tree_lookup_slot - lookup a slot in a radix tree
1063 * @root: radix tree root
1064 * @index: index key
1065 *
1066 * Returns: the slot corresponding to the position @index in the
1067 * radix tree @root. This is useful for update-if-exists operations.
1068 *
1069 * This function can be called under rcu_read_lock iff the slot is not
1070 * modified by radix_tree_replace_slot, otherwise it must be called
1071 * exclusive from other writers. Any dereference of the slot must be done
1072 * using radix_tree_deref_slot.
1073 */
1074void __rcu **radix_tree_lookup_slot(const struct radix_tree_root *root,
1075 unsigned long index)
1076{
1077 void __rcu **slot;
1078
1079 if (!__radix_tree_lookup(root, index, NULL, &slot))
1080 return NULL;
1081 return slot;
1082}
1083EXPORT_SYMBOL(radix_tree_lookup_slot);
1084
1085/**
1086 * radix_tree_lookup - perform lookup operation on a radix tree
1087 * @root: radix tree root
1088 * @index: index key
1089 *
1090 * Lookup the item at the position @index in the radix tree @root.
1091 *
1092 * This function can be called under rcu_read_lock, however the caller
1093 * must manage lifetimes of leaf nodes (eg. RCU may also be used to free
1094 * them safely). No RCU barriers are required to access or modify the
1095 * returned item, however.
1096 */
1097void *radix_tree_lookup(const struct radix_tree_root *root, unsigned long index)
1098{
1099 return __radix_tree_lookup(root, index, NULL, NULL);
1100}
1101EXPORT_SYMBOL(radix_tree_lookup);
1102
1103static inline void replace_sibling_entries(struct radix_tree_node *node,
1104 void __rcu **slot, int count, int exceptional)
1105{
1106#ifdef CONFIG_RADIX_TREE_MULTIORDER
1107 void *ptr = node_to_entry(slot);
1108 unsigned offset = get_slot_offset(node, slot) + 1;
1109
1110 while (offset < RADIX_TREE_MAP_SIZE) {
1111 if (rcu_dereference_raw(node->slots[offset]) != ptr)
1112 break;
1113 if (count < 0) {
1114 node->slots[offset] = NULL;
1115 node->count--;
1116 }
1117 node->exceptional += exceptional;
1118 offset++;
1119 }
1120#endif
1121}
1122
1123static void replace_slot(void __rcu **slot, void *item,
1124 struct radix_tree_node *node, int count, int exceptional)
1125{
1126 if (WARN_ON_ONCE(radix_tree_is_internal_node(item)))
1127 return;
1128
1129 if (node && (count || exceptional)) {
1130 node->count += count;
1131 node->exceptional += exceptional;
1132 replace_sibling_entries(node, slot, count, exceptional);
1133 }
1134
1135 rcu_assign_pointer(*slot, item);
1136}
1137
1138static bool node_tag_get(const struct radix_tree_root *root,
1139 const struct radix_tree_node *node,
1140 unsigned int tag, unsigned int offset)
1141{
1142 if (node)
1143 return tag_get(node, tag, offset);
1144 return root_tag_get(root, tag);
1145}
1146
1147/*
1148 * IDR users want to be able to store NULL in the tree, so if the slot isn't
1149 * free, don't adjust the count, even if it's transitioning between NULL and
1150 * non-NULL. For the IDA, we mark slots as being IDR_FREE while they still
1151 * have empty bits, but it only stores NULL in slots when they're being
1152 * deleted.
1153 */
1154static int calculate_count(struct radix_tree_root *root,
1155 struct radix_tree_node *node, void __rcu **slot,
1156 void *item, void *old)
1157{
1158 if (is_idr(root)) {
1159 unsigned offset = get_slot_offset(node, slot);
1160 bool free = node_tag_get(root, node, IDR_FREE, offset);
1161 if (!free)
1162 return 0;
1163 if (!old)
1164 return 1;
1165 }
1166 return !!item - !!old;
1167}
1168
1169/**
1170 * __radix_tree_replace - replace item in a slot
1171 * @root: radix tree root
1172 * @node: pointer to tree node
1173 * @slot: pointer to slot in @node
1174 * @item: new item to store in the slot.
1175 * @update_node: callback for changing leaf nodes
1176 *
1177 * For use with __radix_tree_lookup(). Caller must hold tree write locked
1178 * across slot lookup and replacement.
1179 */
1180void __radix_tree_replace(struct radix_tree_root *root,
1181 struct radix_tree_node *node,
1182 void __rcu **slot, void *item,
1183 radix_tree_update_node_t update_node)
1184{
1185 void *old = rcu_dereference_raw(*slot);
1186 int exceptional = !!radix_tree_exceptional_entry(item) -
1187 !!radix_tree_exceptional_entry(old);
1188 int count = calculate_count(root, node, slot, item, old);
1189
1190 /*
1191 * This function supports replacing exceptional entries and
1192 * deleting entries, but that needs accounting against the
1193 * node unless the slot is root->rnode.
1194 */
1195 WARN_ON_ONCE(!node && (slot != (void __rcu **)&root->rnode) &&
1196 (count || exceptional));
1197 replace_slot(slot, item, node, count, exceptional);
1198
1199 if (!node)
1200 return;
1201
1202 if (update_node)
1203 update_node(node);
1204
1205 delete_node(root, node, update_node);
1206}
1207
1208/**
1209 * radix_tree_replace_slot - replace item in a slot
1210 * @root: radix tree root
1211 * @slot: pointer to slot
1212 * @item: new item to store in the slot.
1213 *
1214 * For use with radix_tree_lookup_slot(), radix_tree_gang_lookup_slot(),
1215 * radix_tree_gang_lookup_tag_slot(). Caller must hold tree write locked
1216 * across slot lookup and replacement.
1217 *
1218 * NOTE: This cannot be used to switch between non-entries (empty slots),
1219 * regular entries, and exceptional entries, as that requires accounting
1220 * inside the radix tree node. When switching from one type of entry or
1221 * deleting, use __radix_tree_lookup() and __radix_tree_replace() or
1222 * radix_tree_iter_replace().
1223 */
1224void radix_tree_replace_slot(struct radix_tree_root *root,
1225 void __rcu **slot, void *item)
1226{
1227 __radix_tree_replace(root, NULL, slot, item, NULL);
1228}
1229EXPORT_SYMBOL(radix_tree_replace_slot);
1230
1231/**
1232 * radix_tree_iter_replace - replace item in a slot
1233 * @root: radix tree root
1234 * @slot: pointer to slot
1235 * @item: new item to store in the slot.
1236 *
1237 * For use with radix_tree_split() and radix_tree_for_each_slot().
1238 * Caller must hold tree write locked across split and replacement.
1239 */
1240void radix_tree_iter_replace(struct radix_tree_root *root,
1241 const struct radix_tree_iter *iter,
1242 void __rcu **slot, void *item)
1243{
1244 __radix_tree_replace(root, iter->node, slot, item, NULL);
1245}
1246
1247#ifdef CONFIG_RADIX_TREE_MULTIORDER
1248/**
1249 * radix_tree_join - replace multiple entries with one multiorder entry
1250 * @root: radix tree root
1251 * @index: an index inside the new entry
1252 * @order: order of the new entry
1253 * @item: new entry
1254 *
1255 * Call this function to replace several entries with one larger entry.
1256 * The existing entries are presumed to not need freeing as a result of
1257 * this call.
1258 *
1259 * The replacement entry will have all the tags set on it that were set
1260 * on any of the entries it is replacing.
1261 */
1262int radix_tree_join(struct radix_tree_root *root, unsigned long index,
1263 unsigned order, void *item)
1264{
1265 struct radix_tree_node *node;
1266 void __rcu **slot;
1267 int error;
1268
1269 BUG_ON(radix_tree_is_internal_node(item));
1270
1271 error = __radix_tree_create(root, index, order, &node, &slot);
1272 if (!error)
1273 error = insert_entries(node, slot, item, order, true);
1274 if (error > 0)
1275 error = 0;
1276
1277 return error;
1278}
1279
1280/**
1281 * radix_tree_split - Split an entry into smaller entries
1282 * @root: radix tree root
1283 * @index: An index within the large entry
1284 * @order: Order of new entries
1285 *
1286 * Call this function as the first step in replacing a multiorder entry
1287 * with several entries of lower order. After this function returns,
1288 * loop over the relevant portion of the tree using radix_tree_for_each_slot()
1289 * and call radix_tree_iter_replace() to set up each new entry.
1290 *
1291 * The tags from this entry are replicated to all the new entries.
1292 *
1293 * The radix tree should be locked against modification during the entire
1294 * replacement operation. Lock-free lookups will see RADIX_TREE_RETRY which
1295 * should prompt RCU walkers to restart the lookup from the root.
1296 */
1297int radix_tree_split(struct radix_tree_root *root, unsigned long index,
1298 unsigned order)
1299{
1300 struct radix_tree_node *parent, *node, *child;
1301 void __rcu **slot;
1302 unsigned int offset, end;
1303 unsigned n, tag, tags = 0;
1304 gfp_t gfp = root_gfp_mask(root);
1305
1306 if (!__radix_tree_lookup(root, index, &parent, &slot))
1307 return -ENOENT;
1308 if (!parent)
1309 return -ENOENT;
1310
1311 offset = get_slot_offset(parent, slot);
1312
1313 for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
1314 if (tag_get(parent, tag, offset))
1315 tags |= 1 << tag;
1316
1317 for (end = offset + 1; end < RADIX_TREE_MAP_SIZE; end++) {
1318 if (!is_sibling_entry(parent,
1319 rcu_dereference_raw(parent->slots[end])))
1320 break;
1321 for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
1322 if (tags & (1 << tag))
1323 tag_set(parent, tag, end);
1324 /* rcu_assign_pointer ensures tags are set before RETRY */
1325 rcu_assign_pointer(parent->slots[end], RADIX_TREE_RETRY);
1326 }
1327 rcu_assign_pointer(parent->slots[offset], RADIX_TREE_RETRY);
1328 parent->exceptional -= (end - offset);
1329
1330 if (order == parent->shift)
1331 return 0;
1332 if (order > parent->shift) {
1333 while (offset < end)
1334 offset += insert_entries(parent, &parent->slots[offset],
1335 RADIX_TREE_RETRY, order, true);
1336 return 0;
1337 }
1338
1339 node = parent;
1340
1341 for (;;) {
1342 if (node->shift > order) {
1343 child = radix_tree_node_alloc(gfp, node, root,
1344 node->shift - RADIX_TREE_MAP_SHIFT,
1345 offset, 0, 0);
1346 if (!child)
1347 goto nomem;
1348 if (node != parent) {
1349 node->count++;
1350 rcu_assign_pointer(node->slots[offset],
1351 node_to_entry(child));
1352 for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
1353 if (tags & (1 << tag))
1354 tag_set(node, tag, offset);
1355 }
1356
1357 node = child;
1358 offset = 0;
1359 continue;
1360 }
1361
1362 n = insert_entries(node, &node->slots[offset],
1363 RADIX_TREE_RETRY, order, false);
1364 BUG_ON(n > RADIX_TREE_MAP_SIZE);
1365
1366 for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
1367 if (tags & (1 << tag))
1368 tag_set(node, tag, offset);
1369 offset += n;
1370
1371 while (offset == RADIX_TREE_MAP_SIZE) {
1372 if (node == parent)
1373 break;
1374 offset = node->offset;
1375 child = node;
1376 node = node->parent;
1377 rcu_assign_pointer(node->slots[offset],
1378 node_to_entry(child));
1379 offset++;
1380 }
1381 if ((node == parent) && (offset == end))
1382 return 0;
1383 }
1384
1385 nomem:
1386 /* Shouldn't happen; did user forget to preload? */
1387 /* TODO: free all the allocated nodes */
1388 WARN_ON(1);
1389 return -ENOMEM;
1390}
1391#endif
1392
1393static void node_tag_set(struct radix_tree_root *root,
1394 struct radix_tree_node *node,
1395 unsigned int tag, unsigned int offset)
1396{
1397 while (node) {
1398 if (tag_get(node, tag, offset))
1399 return;
1400 tag_set(node, tag, offset);
1401 offset = node->offset;
1402 node = node->parent;
1403 }
1404
1405 if (!root_tag_get(root, tag))
1406 root_tag_set(root, tag);
1407}
1408
1409/**
1410 * radix_tree_tag_set - set a tag on a radix tree node
1411 * @root: radix tree root
1412 * @index: index key
1413 * @tag: tag index
1414 *
1415 * Set the search tag (which must be < RADIX_TREE_MAX_TAGS)
1416 * corresponding to @index in the radix tree. From
1417 * the root all the way down to the leaf node.
1418 *
1419 * Returns the address of the tagged item. Setting a tag on a not-present
1420 * item is a bug.
1421 */
1422void *radix_tree_tag_set(struct radix_tree_root *root,
1423 unsigned long index, unsigned int tag)
1424{
1425 struct radix_tree_node *node, *parent;
1426 unsigned long maxindex;
1427
1428 radix_tree_load_root(root, &node, &maxindex);
1429 BUG_ON(index > maxindex);
1430
1431 while (radix_tree_is_internal_node(node)) {
1432 unsigned offset;
1433
1434 parent = entry_to_node(node);
1435 offset = radix_tree_descend(parent, &node, index);
1436 BUG_ON(!node);
1437
1438 if (!tag_get(parent, tag, offset))
1439 tag_set(parent, tag, offset);
1440 }
1441
1442 /* set the root's tag bit */
1443 if (!root_tag_get(root, tag))
1444 root_tag_set(root, tag);
1445
1446 return node;
1447}
1448EXPORT_SYMBOL(radix_tree_tag_set);
1449
1450/**
1451 * radix_tree_iter_tag_set - set a tag on the current iterator entry
1452 * @root: radix tree root
1453 * @iter: iterator state
1454 * @tag: tag to set
1455 */
1456void radix_tree_iter_tag_set(struct radix_tree_root *root,
1457 const struct radix_tree_iter *iter, unsigned int tag)
1458{
1459 node_tag_set(root, iter->node, tag, iter_offset(iter));
1460}
1461
1462static void node_tag_clear(struct radix_tree_root *root,
1463 struct radix_tree_node *node,
1464 unsigned int tag, unsigned int offset)
1465{
1466 while (node) {
1467 if (!tag_get(node, tag, offset))
1468 return;
1469 tag_clear(node, tag, offset);
1470 if (any_tag_set(node, tag))
1471 return;
1472
1473 offset = node->offset;
1474 node = node->parent;
1475 }
1476
1477 /* clear the root's tag bit */
1478 if (root_tag_get(root, tag))
1479 root_tag_clear(root, tag);
1480}
1481
1482/**
1483 * radix_tree_tag_clear - clear a tag on a radix tree node
1484 * @root: radix tree root
1485 * @index: index key
1486 * @tag: tag index
1487 *
1488 * Clear the search tag (which must be < RADIX_TREE_MAX_TAGS)
1489 * corresponding to @index in the radix tree. If this causes
1490 * the leaf node to have no tags set then clear the tag in the
1491 * next-to-leaf node, etc.
1492 *
1493 * Returns the address of the tagged item on success, else NULL. ie:
1494 * has the same return value and semantics as radix_tree_lookup().
1495 */
1496void *radix_tree_tag_clear(struct radix_tree_root *root,
1497 unsigned long index, unsigned int tag)
1498{
1499 struct radix_tree_node *node, *parent;
1500 unsigned long maxindex;
1501 int uninitialized_var(offset);
1502
1503 radix_tree_load_root(root, &node, &maxindex);
1504 if (index > maxindex)
1505 return NULL;
1506
1507 parent = NULL;
1508
1509 while (radix_tree_is_internal_node(node)) {
1510 parent = entry_to_node(node);
1511 offset = radix_tree_descend(parent, &node, index);
1512 }
1513
1514 if (node)
1515 node_tag_clear(root, parent, tag, offset);
1516
1517 return node;
1518}
1519EXPORT_SYMBOL(radix_tree_tag_clear);
1520
1521/**
1522 * radix_tree_iter_tag_clear - clear a tag on the current iterator entry
1523 * @root: radix tree root
1524 * @iter: iterator state
1525 * @tag: tag to clear
1526 */
1527void radix_tree_iter_tag_clear(struct radix_tree_root *root,
1528 const struct radix_tree_iter *iter, unsigned int tag)
1529{
1530 node_tag_clear(root, iter->node, tag, iter_offset(iter));
1531}
1532
1533/**
1534 * radix_tree_tag_get - get a tag on a radix tree node
1535 * @root: radix tree root
1536 * @index: index key
1537 * @tag: tag index (< RADIX_TREE_MAX_TAGS)
1538 *
1539 * Return values:
1540 *
1541 * 0: tag not present or not set
1542 * 1: tag set
1543 *
1544 * Note that the return value of this function may not be relied on, even if
1545 * the RCU lock is held, unless tag modification and node deletion are excluded
1546 * from concurrency.
1547 */
1548int radix_tree_tag_get(const struct radix_tree_root *root,
1549 unsigned long index, unsigned int tag)
1550{
1551 struct radix_tree_node *node, *parent;
1552 unsigned long maxindex;
1553
1554 if (!root_tag_get(root, tag))
1555 return 0;
1556
1557 radix_tree_load_root(root, &node, &maxindex);
1558 if (index > maxindex)
1559 return 0;
1560
1561 while (radix_tree_is_internal_node(node)) {
1562 unsigned offset;
1563
1564 parent = entry_to_node(node);
1565 offset = radix_tree_descend(parent, &node, index);
1566
1567 if (!tag_get(parent, tag, offset))
1568 return 0;
1569 if (node == RADIX_TREE_RETRY)
1570 break;
1571 }
1572
1573 return 1;
1574}
1575EXPORT_SYMBOL(radix_tree_tag_get);
1576
1577static inline void __set_iter_shift(struct radix_tree_iter *iter,
1578 unsigned int shift)
1579{
1580#ifdef CONFIG_RADIX_TREE_MULTIORDER
1581 iter->shift = shift;
1582#endif
1583}
1584
1585/* Construct iter->tags bit-mask from node->tags[tag] array */
1586static void set_iter_tags(struct radix_tree_iter *iter,
1587 struct radix_tree_node *node, unsigned offset,
1588 unsigned tag)
1589{
1590 unsigned tag_long = offset / BITS_PER_LONG;
1591 unsigned tag_bit = offset % BITS_PER_LONG;
1592
1593 if (!node) {
1594 iter->tags = 1;
1595 return;
1596 }
1597
1598 iter->tags = node->tags[tag][tag_long] >> tag_bit;
1599
1600 /* This never happens if RADIX_TREE_TAG_LONGS == 1 */
1601 if (tag_long < RADIX_TREE_TAG_LONGS - 1) {
1602 /* Pick tags from next element */
1603 if (tag_bit)
1604 iter->tags |= node->tags[tag][tag_long + 1] <<
1605 (BITS_PER_LONG - tag_bit);
1606 /* Clip chunk size, here only BITS_PER_LONG tags */
1607 iter->next_index = __radix_tree_iter_add(iter, BITS_PER_LONG);
1608 }
1609}
1610
1611#ifdef CONFIG_RADIX_TREE_MULTIORDER
1612static void __rcu **skip_siblings(struct radix_tree_node **nodep,
1613 void __rcu **slot, struct radix_tree_iter *iter)
1614{
1615 while (iter->index < iter->next_index) {
1616 *nodep = rcu_dereference_raw(*slot);
1617 if (*nodep && !is_sibling_entry(iter->node, *nodep))
1618 return slot;
1619 slot++;
1620 iter->index = __radix_tree_iter_add(iter, 1);
1621 iter->tags >>= 1;
1622 }
1623
1624 *nodep = NULL;
1625 return NULL;
1626}
1627
1628void __rcu **__radix_tree_next_slot(void __rcu **slot,
1629 struct radix_tree_iter *iter, unsigned flags)
1630{
1631 unsigned tag = flags & RADIX_TREE_ITER_TAG_MASK;
1632 struct radix_tree_node *node;
1633
1634 slot = skip_siblings(&node, slot, iter);
1635
1636 while (radix_tree_is_internal_node(node)) {
1637 unsigned offset;
1638 unsigned long next_index;
1639
1640 if (node == RADIX_TREE_RETRY)
1641 return slot;
1642 node = entry_to_node(node);
1643 iter->node = node;
1644 iter->shift = node->shift;
1645
1646 if (flags & RADIX_TREE_ITER_TAGGED) {
1647 offset = radix_tree_find_next_bit(node, tag, 0);
1648 if (offset == RADIX_TREE_MAP_SIZE)
1649 return NULL;
1650 slot = &node->slots[offset];
1651 iter->index = __radix_tree_iter_add(iter, offset);
1652 set_iter_tags(iter, node, offset, tag);
1653 node = rcu_dereference_raw(*slot);
1654 } else {
1655 offset = 0;
1656 slot = &node->slots[0];
1657 for (;;) {
1658 node = rcu_dereference_raw(*slot);
1659 if (node)
1660 break;
1661 slot++;
1662 offset++;
1663 if (offset == RADIX_TREE_MAP_SIZE)
1664 return NULL;
1665 }
1666 iter->index = __radix_tree_iter_add(iter, offset);
1667 }
1668 if ((flags & RADIX_TREE_ITER_CONTIG) && (offset > 0))
1669 goto none;
1670 next_index = (iter->index | shift_maxindex(iter->shift)) + 1;
1671 if (next_index < iter->next_index)
1672 iter->next_index = next_index;
1673 }
1674
1675 return slot;
1676 none:
1677 iter->next_index = 0;
1678 return NULL;
1679}
1680EXPORT_SYMBOL(__radix_tree_next_slot);
1681#else
1682static void __rcu **skip_siblings(struct radix_tree_node **nodep,
1683 void __rcu **slot, struct radix_tree_iter *iter)
1684{
1685 return slot;
1686}
1687#endif
1688
1689void __rcu **radix_tree_iter_resume(void __rcu **slot,
1690 struct radix_tree_iter *iter)
1691{
1692 struct radix_tree_node *node;
1693
1694 slot++;
1695 iter->index = __radix_tree_iter_add(iter, 1);
1696 skip_siblings(&node, slot, iter);
1697 iter->next_index = iter->index;
1698 iter->tags = 0;
1699 return NULL;
1700}
1701EXPORT_SYMBOL(radix_tree_iter_resume);
1702
1703/**
1704 * radix_tree_next_chunk - find next chunk of slots for iteration
1705 *
1706 * @root: radix tree root
1707 * @iter: iterator state
1708 * @flags: RADIX_TREE_ITER_* flags and tag index
1709 * Returns: pointer to chunk first slot, or NULL if iteration is over
1710 */
1711void __rcu **radix_tree_next_chunk(const struct radix_tree_root *root,
1712 struct radix_tree_iter *iter, unsigned flags)
1713{
1714 unsigned tag = flags & RADIX_TREE_ITER_TAG_MASK;
1715 struct radix_tree_node *node, *child;
1716 unsigned long index, offset, maxindex;
1717
1718 if ((flags & RADIX_TREE_ITER_TAGGED) && !root_tag_get(root, tag))
1719 return NULL;
1720
1721 /*
1722 * Catch next_index overflow after ~0UL. iter->index never overflows
1723 * during iterating; it can be zero only at the beginning.
1724 * And we cannot overflow iter->next_index in a single step,
1725 * because RADIX_TREE_MAP_SHIFT < BITS_PER_LONG.
1726 *
1727 * This condition also used by radix_tree_next_slot() to stop
1728 * contiguous iterating, and forbid switching to the next chunk.
1729 */
1730 index = iter->next_index;
1731 if (!index && iter->index)
1732 return NULL;
1733
1734 restart:
1735 radix_tree_load_root(root, &child, &maxindex);
1736 if (index > maxindex)
1737 return NULL;
1738 if (!child)
1739 return NULL;
1740
1741 if (!radix_tree_is_internal_node(child)) {
1742 /* Single-slot tree */
1743 iter->index = index;
1744 iter->next_index = maxindex + 1;
1745 iter->tags = 1;
1746 iter->node = NULL;
1747 __set_iter_shift(iter, 0);
1748 return (void __rcu **)&root->rnode;
1749 }
1750
1751 do {
1752 node = entry_to_node(child);
1753 offset = radix_tree_descend(node, &child, index);
1754
1755 if ((flags & RADIX_TREE_ITER_TAGGED) ?
1756 !tag_get(node, tag, offset) : !child) {
1757 /* Hole detected */
1758 if (flags & RADIX_TREE_ITER_CONTIG)
1759 return NULL;
1760
1761 if (flags & RADIX_TREE_ITER_TAGGED)
1762 offset = radix_tree_find_next_bit(node, tag,
1763 offset + 1);
1764 else
1765 while (++offset < RADIX_TREE_MAP_SIZE) {
1766 void *slot = rcu_dereference_raw(
1767 node->slots[offset]);
1768 if (is_sibling_entry(node, slot))
1769 continue;
1770 if (slot)
1771 break;
1772 }
1773 index &= ~node_maxindex(node);
1774 index += offset << node->shift;
1775 /* Overflow after ~0UL */
1776 if (!index)
1777 return NULL;
1778 if (offset == RADIX_TREE_MAP_SIZE)
1779 goto restart;
1780 child = rcu_dereference_raw(node->slots[offset]);
1781 }
1782
1783 if (!child)
1784 goto restart;
1785 if (child == RADIX_TREE_RETRY)
1786 break;
1787 } while (radix_tree_is_internal_node(child));
1788
1789 /* Update the iterator state */
1790 iter->index = (index &~ node_maxindex(node)) | (offset << node->shift);
1791 iter->next_index = (index | node_maxindex(node)) + 1;
1792 iter->node = node;
1793 __set_iter_shift(iter, node->shift);
1794
1795 if (flags & RADIX_TREE_ITER_TAGGED)
1796 set_iter_tags(iter, node, offset, tag);
1797
1798 return node->slots + offset;
1799}
1800EXPORT_SYMBOL(radix_tree_next_chunk);
1801
1802/**
1803 * radix_tree_gang_lookup - perform multiple lookup on a radix tree
1804 * @root: radix tree root
1805 * @results: where the results of the lookup are placed
1806 * @first_index: start the lookup from this key
1807 * @max_items: place up to this many items at *results
1808 *
1809 * Performs an index-ascending scan of the tree for present items. Places
1810 * them at *@results and returns the number of items which were placed at
1811 * *@results.
1812 *
1813 * The implementation is naive.
1814 *
1815 * Like radix_tree_lookup, radix_tree_gang_lookup may be called under
1816 * rcu_read_lock. In this case, rather than the returned results being
1817 * an atomic snapshot of the tree at a single point in time, the
1818 * semantics of an RCU protected gang lookup are as though multiple
1819 * radix_tree_lookups have been issued in individual locks, and results
1820 * stored in 'results'.
1821 */
1822unsigned int
1823radix_tree_gang_lookup(const struct radix_tree_root *root, void **results,
1824 unsigned long first_index, unsigned int max_items)
1825{
1826 struct radix_tree_iter iter;
1827 void __rcu **slot;
1828 unsigned int ret = 0;
1829
1830 if (unlikely(!max_items))
1831 return 0;
1832
1833 radix_tree_for_each_slot(slot, root, &iter, first_index) {
1834 results[ret] = rcu_dereference_raw(*slot);
1835 if (!results[ret])
1836 continue;
1837 if (radix_tree_is_internal_node(results[ret])) {
1838 slot = radix_tree_iter_retry(&iter);
1839 continue;
1840 }
1841 if (++ret == max_items)
1842 break;
1843 }
1844
1845 return ret;
1846}
1847EXPORT_SYMBOL(radix_tree_gang_lookup);
1848
1849/**
1850 * radix_tree_gang_lookup_slot - perform multiple slot lookup on radix tree
1851 * @root: radix tree root
1852 * @results: where the results of the lookup are placed
1853 * @indices: where their indices should be placed (but usually NULL)
1854 * @first_index: start the lookup from this key
1855 * @max_items: place up to this many items at *results
1856 *
1857 * Performs an index-ascending scan of the tree for present items. Places
1858 * their slots at *@results and returns the number of items which were
1859 * placed at *@results.
1860 *
1861 * The implementation is naive.
1862 *
1863 * Like radix_tree_gang_lookup as far as RCU and locking goes. Slots must
1864 * be dereferenced with radix_tree_deref_slot, and if using only RCU
1865 * protection, radix_tree_deref_slot may fail requiring a retry.
1866 */
1867unsigned int
1868radix_tree_gang_lookup_slot(const struct radix_tree_root *root,
1869 void __rcu ***results, unsigned long *indices,
1870 unsigned long first_index, unsigned int max_items)
1871{
1872 struct radix_tree_iter iter;
1873 void __rcu **slot;
1874 unsigned int ret = 0;
1875
1876 if (unlikely(!max_items))
1877 return 0;
1878
1879 radix_tree_for_each_slot(slot, root, &iter, first_index) {
1880 results[ret] = slot;
1881 if (indices)
1882 indices[ret] = iter.index;
1883 if (++ret == max_items)
1884 break;
1885 }
1886
1887 return ret;
1888}
1889EXPORT_SYMBOL(radix_tree_gang_lookup_slot);
1890
1891/**
1892 * radix_tree_gang_lookup_tag - perform multiple lookup on a radix tree
1893 * based on a tag
1894 * @root: radix tree root
1895 * @results: where the results of the lookup are placed
1896 * @first_index: start the lookup from this key
1897 * @max_items: place up to this many items at *results
1898 * @tag: the tag index (< RADIX_TREE_MAX_TAGS)
1899 *
1900 * Performs an index-ascending scan of the tree for present items which
1901 * have the tag indexed by @tag set. Places the items at *@results and
1902 * returns the number of items which were placed at *@results.
1903 */
1904unsigned int
1905radix_tree_gang_lookup_tag(const struct radix_tree_root *root, void **results,
1906 unsigned long first_index, unsigned int max_items,
1907 unsigned int tag)
1908{
1909 struct radix_tree_iter iter;
1910 void __rcu **slot;
1911 unsigned int ret = 0;
1912
1913 if (unlikely(!max_items))
1914 return 0;
1915
1916 radix_tree_for_each_tagged(slot, root, &iter, first_index, tag) {
1917 results[ret] = rcu_dereference_raw(*slot);
1918 if (!results[ret])
1919 continue;
1920 if (radix_tree_is_internal_node(results[ret])) {
1921 slot = radix_tree_iter_retry(&iter);
1922 continue;
1923 }
1924 if (++ret == max_items)
1925 break;
1926 }
1927
1928 return ret;
1929}
1930EXPORT_SYMBOL(radix_tree_gang_lookup_tag);
1931
1932/**
1933 * radix_tree_gang_lookup_tag_slot - perform multiple slot lookup on a
1934 * radix tree based on a tag
1935 * @root: radix tree root
1936 * @results: where the results of the lookup are placed
1937 * @first_index: start the lookup from this key
1938 * @max_items: place up to this many items at *results
1939 * @tag: the tag index (< RADIX_TREE_MAX_TAGS)
1940 *
1941 * Performs an index-ascending scan of the tree for present items which
1942 * have the tag indexed by @tag set. Places the slots at *@results and
1943 * returns the number of slots which were placed at *@results.
1944 */
1945unsigned int
1946radix_tree_gang_lookup_tag_slot(const struct radix_tree_root *root,
1947 void __rcu ***results, unsigned long first_index,
1948 unsigned int max_items, unsigned int tag)
1949{
1950 struct radix_tree_iter iter;
1951 void __rcu **slot;
1952 unsigned int ret = 0;
1953
1954 if (unlikely(!max_items))
1955 return 0;
1956
1957 radix_tree_for_each_tagged(slot, root, &iter, first_index, tag) {
1958 results[ret] = slot;
1959 if (++ret == max_items)
1960 break;
1961 }
1962
1963 return ret;
1964}
1965EXPORT_SYMBOL(radix_tree_gang_lookup_tag_slot);
1966
1967/**
1968 * __radix_tree_delete_node - try to free node after clearing a slot
1969 * @root: radix tree root
1970 * @node: node containing @index
1971 * @update_node: callback for changing leaf nodes
1972 *
1973 * After clearing the slot at @index in @node from radix tree
1974 * rooted at @root, call this function to attempt freeing the
1975 * node and shrinking the tree.
1976 */
1977void __radix_tree_delete_node(struct radix_tree_root *root,
1978 struct radix_tree_node *node,
1979 radix_tree_update_node_t update_node)
1980{
1981 delete_node(root, node, update_node);
1982}
1983
1984static bool __radix_tree_delete(struct radix_tree_root *root,
1985 struct radix_tree_node *node, void __rcu **slot)
1986{
1987 void *old = rcu_dereference_raw(*slot);
1988 int exceptional = radix_tree_exceptional_entry(old) ? -1 : 0;
1989 unsigned offset = get_slot_offset(node, slot);
1990 int tag;
1991
1992 if (is_idr(root))
1993 node_tag_set(root, node, IDR_FREE, offset);
1994 else
1995 for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
1996 node_tag_clear(root, node, tag, offset);
1997
1998 replace_slot(slot, NULL, node, -1, exceptional);
1999 return node && delete_node(root, node, NULL);
2000}
2001
2002/**
2003 * radix_tree_iter_delete - delete the entry at this iterator position
2004 * @root: radix tree root
2005 * @iter: iterator state
2006 * @slot: pointer to slot
2007 *
2008 * Delete the entry at the position currently pointed to by the iterator.
2009 * This may result in the current node being freed; if it is, the iterator
2010 * is advanced so that it will not reference the freed memory. This
2011 * function may be called without any locking if there are no other threads
2012 * which can access this tree.
2013 */
2014void radix_tree_iter_delete(struct radix_tree_root *root,
2015 struct radix_tree_iter *iter, void __rcu **slot)
2016{
2017 if (__radix_tree_delete(root, iter->node, slot))
2018 iter->index = iter->next_index;
2019}
2020EXPORT_SYMBOL(radix_tree_iter_delete);
2021
2022/**
2023 * radix_tree_delete_item - delete an item from a radix tree
2024 * @root: radix tree root
2025 * @index: index key
2026 * @item: expected item
2027 *
2028 * Remove @item at @index from the radix tree rooted at @root.
2029 *
2030 * Return: the deleted entry, or %NULL if it was not present
2031 * or the entry at the given @index was not @item.
2032 */
2033void *radix_tree_delete_item(struct radix_tree_root *root,
2034 unsigned long index, void *item)
2035{
2036 struct radix_tree_node *node = NULL;
2037 void __rcu **slot = NULL;
2038 void *entry;
2039
2040 entry = __radix_tree_lookup(root, index, &node, &slot);
2041 if (!slot)
2042 return NULL;
2043 if (!entry && (!is_idr(root) || node_tag_get(root, node, IDR_FREE,
2044 get_slot_offset(node, slot))))
2045 return NULL;
2046
2047 if (item && entry != item)
2048 return NULL;
2049
2050 __radix_tree_delete(root, node, slot);
2051
2052 return entry;
2053}
2054EXPORT_SYMBOL(radix_tree_delete_item);
2055
2056/**
2057 * radix_tree_delete - delete an entry from a radix tree
2058 * @root: radix tree root
2059 * @index: index key
2060 *
2061 * Remove the entry at @index from the radix tree rooted at @root.
2062 *
2063 * Return: The deleted entry, or %NULL if it was not present.
2064 */
2065void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
2066{
2067 return radix_tree_delete_item(root, index, NULL);
2068}
2069EXPORT_SYMBOL(radix_tree_delete);
2070
2071void radix_tree_clear_tags(struct radix_tree_root *root,
2072 struct radix_tree_node *node,
2073 void __rcu **slot)
2074{
2075 if (node) {
2076 unsigned int tag, offset = get_slot_offset(node, slot);
2077 for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
2078 node_tag_clear(root, node, tag, offset);
2079 } else {
2080 root_tag_clear_all(root);
2081 }
2082}
2083
2084/**
2085 * radix_tree_tagged - test whether any items in the tree are tagged
2086 * @root: radix tree root
2087 * @tag: tag to test
2088 */
2089int radix_tree_tagged(const struct radix_tree_root *root, unsigned int tag)
2090{
2091 return root_tag_get(root, tag);
2092}
2093EXPORT_SYMBOL(radix_tree_tagged);
2094
2095/**
2096 * idr_preload - preload for idr_alloc()
2097 * @gfp_mask: allocation mask to use for preloading
2098 *
2099 * Preallocate memory to use for the next call to idr_alloc(). This function
2100 * returns with preemption disabled. It will be enabled by idr_preload_end().
2101 */
2102void idr_preload(gfp_t gfp_mask)
2103{
2104 if (__radix_tree_preload(gfp_mask, IDR_PRELOAD_SIZE))
2105 preempt_disable();
2106}
2107EXPORT_SYMBOL(idr_preload);
2108
2109/**
2110 * ida_pre_get - reserve resources for ida allocation
2111 * @ida: ida handle
2112 * @gfp: memory allocation flags
2113 *
2114 * This function should be called before calling ida_get_new_above(). If it
2115 * is unable to allocate memory, it will return %0. On success, it returns %1.
2116 */
2117int ida_pre_get(struct ida *ida, gfp_t gfp)
2118{
2119 /*
2120 * The IDA API has no preload_end() equivalent. Instead,
2121 * ida_get_new() can return -EAGAIN, prompting the caller
2122 * to return to the ida_pre_get() step.
2123 */
2124 if (!__radix_tree_preload(gfp, IDA_PRELOAD_SIZE))
2125 preempt_enable();
2126
2127 if (!this_cpu_read(ida_bitmap)) {
2128 struct ida_bitmap *bitmap = kzalloc(sizeof(*bitmap), gfp);
2129 if (!bitmap)
2130 return 0;
2131 if (this_cpu_cmpxchg(ida_bitmap, NULL, bitmap))
2132 kfree(bitmap);
2133 }
2134
2135 return 1;
2136}
2137EXPORT_SYMBOL(ida_pre_get);
2138
2139void __rcu **idr_get_free(struct radix_tree_root *root,
2140 struct radix_tree_iter *iter, gfp_t gfp,
2141 unsigned long max)
2142{
2143 struct radix_tree_node *node = NULL, *child;
2144 void __rcu **slot = (void __rcu **)&root->rnode;
2145 unsigned long maxindex, start = iter->next_index;
2146 unsigned int shift, offset = 0;
2147
2148 grow:
2149 shift = radix_tree_load_root(root, &child, &maxindex);
2150 if (!radix_tree_tagged(root, IDR_FREE))
2151 start = max(start, maxindex + 1);
2152 if (start > max)
2153 return ERR_PTR(-ENOSPC);
2154
2155 if (start > maxindex) {
2156 int error = radix_tree_extend(root, gfp, start, shift);
2157 if (error < 0)
2158 return ERR_PTR(error);
2159 shift = error;
2160 child = rcu_dereference_raw(root->rnode);
2161 }
2162
2163 while (shift) {
2164 shift -= RADIX_TREE_MAP_SHIFT;
2165 if (child == NULL) {
2166 /* Have to add a child node. */
2167 child = radix_tree_node_alloc(gfp, node, root, shift,
2168 offset, 0, 0);
2169 if (!child)
2170 return ERR_PTR(-ENOMEM);
2171 all_tag_set(child, IDR_FREE);
2172 rcu_assign_pointer(*slot, node_to_entry(child));
2173 if (node)
2174 node->count++;
2175 } else if (!radix_tree_is_internal_node(child))
2176 break;
2177
2178 node = entry_to_node(child);
2179 offset = radix_tree_descend(node, &child, start);
2180 if (!tag_get(node, IDR_FREE, offset)) {
2181 offset = radix_tree_find_next_bit(node, IDR_FREE,
2182 offset + 1);
2183 start = next_index(start, node, offset);
2184 if (start > max)
2185 return ERR_PTR(-ENOSPC);
2186 while (offset == RADIX_TREE_MAP_SIZE) {
2187 offset = node->offset + 1;
2188 node = node->parent;
2189 if (!node)
2190 goto grow;
2191 shift = node->shift;
2192 }
2193 child = rcu_dereference_raw(node->slots[offset]);
2194 }
2195 slot = &node->slots[offset];
2196 }
2197
2198 iter->index = start;
2199 if (node)
2200 iter->next_index = 1 + min(max, (start | node_maxindex(node)));
2201 else
2202 iter->next_index = 1;
2203 iter->node = node;
2204 __set_iter_shift(iter, shift);
2205 set_iter_tags(iter, node, offset, IDR_FREE);
2206
2207 return slot;
2208}
2209
2210/**
2211 * idr_destroy - release all internal memory from an IDR
2212 * @idr: idr handle
2213 *
2214 * After this function is called, the IDR is empty, and may be reused or
2215 * the data structure containing it may be freed.
2216 *
2217 * A typical clean-up sequence for objects stored in an idr tree will use
2218 * idr_for_each() to free all objects, if necessary, then idr_destroy() to
2219 * free the memory used to keep track of those objects.
2220 */
2221void idr_destroy(struct idr *idr)
2222{
2223 struct radix_tree_node *node = rcu_dereference_raw(idr->idr_rt.rnode);
2224 if (radix_tree_is_internal_node(node))
2225 radix_tree_free_nodes(node);
2226 idr->idr_rt.rnode = NULL;
2227 root_tag_set(&idr->idr_rt, IDR_FREE);
2228}
2229EXPORT_SYMBOL(idr_destroy);
2230
2231static void
2232radix_tree_node_ctor(void *arg)
2233{
2234 struct radix_tree_node *node = arg;
2235
2236 memset(node, 0, sizeof(*node));
2237 INIT_LIST_HEAD(&node->private_list);
2238}
2239
2240static __init unsigned long __maxindex(unsigned int height)
2241{
2242 unsigned int width = height * RADIX_TREE_MAP_SHIFT;
2243 int shift = RADIX_TREE_INDEX_BITS - width;
2244
2245 if (shift < 0)
2246 return ~0UL;
2247 if (shift >= BITS_PER_LONG)
2248 return 0UL;
2249 return ~0UL >> shift;
2250}
2251
2252static __init void radix_tree_init_maxnodes(void)
2253{
2254 unsigned long height_to_maxindex[RADIX_TREE_MAX_PATH + 1];
2255 unsigned int i, j;
2256
2257 for (i = 0; i < ARRAY_SIZE(height_to_maxindex); i++)
2258 height_to_maxindex[i] = __maxindex(i);
2259 for (i = 0; i < ARRAY_SIZE(height_to_maxnodes); i++) {
2260 for (j = i; j > 0; j--)
2261 height_to_maxnodes[i] += height_to_maxindex[j - 1] + 1;
2262 }
2263}
2264
2265static int radix_tree_cpu_dead(unsigned int cpu)
2266{
2267 struct radix_tree_preload *rtp;
2268 struct radix_tree_node *node;
2269
2270 /* Free per-cpu pool of preloaded nodes */
2271 rtp = &per_cpu(radix_tree_preloads, cpu);
2272 while (rtp->nr) {
2273 node = rtp->nodes;
2274 rtp->nodes = node->parent;
2275 kmem_cache_free(radix_tree_node_cachep, node);
2276 rtp->nr--;
2277 }
2278 kfree(per_cpu(ida_bitmap, cpu));
2279 per_cpu(ida_bitmap, cpu) = NULL;
2280 return 0;
2281}
2282
2283void __init radix_tree_init(void)
2284{
2285 int ret;
2286
2287 BUILD_BUG_ON(RADIX_TREE_MAX_TAGS + __GFP_BITS_SHIFT > 32);
2288 BUILD_BUG_ON(ROOT_IS_IDR & ~GFP_ZONEMASK);
2289 radix_tree_node_cachep = kmem_cache_create("radix_tree_node",
2290 sizeof(struct radix_tree_node), 0,
2291 SLAB_PANIC | SLAB_RECLAIM_ACCOUNT,
2292 radix_tree_node_ctor);
2293 radix_tree_init_maxnodes();
2294 ret = cpuhp_setup_state_nocalls(CPUHP_RADIX_DEAD, "lib/radix:dead",
2295 NULL, radix_tree_cpu_dead);
2296 WARN_ON(ret < 0);
2297}